SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                    FORM 6-K


                            Report of Foreign Issuer

                      Pursuant to Rule 13a-16 or 15d-16 of
                       the Securities Exchange Act of 1934


                        For the Month of January 24 2003

                         Commission file number: 0-30924


                                   MARCONI PLC

             (Exact name of Registrant as specified in its Charter)


                                   4th Floor
                                 Regents Place
                                338 Euston Road
                                    London
                                    NW1 3BT
                    (Address of principal executive offices)


(Indicate by check mark whether the registrant files or will file annual
reports under cover Form 20-F or Form 40-F.)


                             Form 20-F X   Form 40-F


(Indicate by check mark whether the registrant by furnishing the information
contained in this Form is also thereby furnishing the information to the
Commission pursuant to Rule 12g3-2(b) under the Securities Exchange
Act of 1934.)


                                   Yes   No X


              CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS


In order to utilize the "Safe Harbor"  provisions  of the United States  Private
Securities  Litigation Reform Act of 1995 (the "Reform Act"),  Marconi plc ( the
"Company")  is  providing  the  following  cautionary   statement.   Except  for
historical information contained herein,  statements contained in this Report on
Form 6-K may constitute  "forward-looking  statements" within the meaning of the
Reform Act. The words "believe",  "anticipate",  "expect", "intend", "estimate",
"plan",  "assume",  "positioned",   "will",  "may",  "risk"  and  other  similar
expressions which are predictions of or indicate future events and future trends
which do not relate to historical matters identify  forward-looking  statements.
Reliance should not be placed on such statements  because they involve known and
unknown  risks,  uncertainties  and other factors which are in some cases beyond
the control of the Company,  together with its subsidiaries  (the "Group"),  and
may cause the actual results, performance or achievements of the Group to differ
materially  from  anticipated   future  results,   performance  or  achievements
expressed or implied by such forward-looking  statements (and from past results,
performance or  achievement).  Certain  factors that may cause such  differences
include  but are not  limited  to the  following:  (1) any major  disruption  in
production  at our key  facilities;  (2) changes in the  environmental,  tax and
other laws and regulations,  which, among other things,  could cause us to incur
substantial additional capital expenditures and operation and maintenance costs;
and (3) adverse  changes in the markets for our products,  including as a result
of increased  competition in the highly  competitive  international  markets for
such products. These and other risks, uncertainties and factors are discussed in
the  Company's  Registration  Statement  on Form F-1 and other  filings with the
Securities and Exchange  Commission,  including this Form 6-K.  Shareholders and
prospective  investors  are  cautioned  not to  place  undue  reliance  on these
forward-looking  statements which speak only as to the Company's  judgment as of
the date hereof.  Any such  forward-looking  statements are not intended to give
any  assurance as to future  results.  The Company  undertakes  no obligation to
publicly update or revise any of these  forward-looking  statements,  whether to
reflect new information or future events or circumstances or otherwise.




                                  Marconi plc

                      TRADING UPDATE FOR THE THREE MONTHS

                             ENDED 31 DECEMBER 2002



  * Solid performance despite continued tough market conditions

  * Core sales GBP456 million; sequential decline of 5%, similar to level
    reported in the previous quarter

  * Improved operating performance compared to previous quarter

  * Continued improvement in gross margin despite lower sales volumes

  * Core operating cost annual run-rate reduced to around GBP550 million by 31
    December 2002; on track to achieve GBP520 million target run-rate by the end
    of the financial year; further actions initiated to reach GBP450 million
    target during the financial year ending 31 March 2004

  * Significant progress towards sustained operating cash breakeven position;
    positive operating cash inflow during the quarter; total cash balance at 31
    December 2002 broadly stable compared to 30 September 2002

  * Restructuring expected to be implemented on the terms set out in the
    announcement on 29 August 2002, as subsequently amended on 16 December 2002

  * The Group remains on track to distribute GBP260 million in cash to Scheme
    creditors as part of the Restructuring (including GBP95 million interest
    accrued at 15 October 2002 and already paid to financial creditors)

  * Further progress made on the Scheme documentation and the Prospectus for
    listing of Marconi Corporation plc; finalisation of documentation expected
    within next few weeks; overall completion of Restructuring now expected in
    April.



London - 24 January 2003 - Marconi (MONI) today provided a trading update
relating to the three months ended 31 December 2002. All information in this
trading update is based on preliminary, unaudited data from Marconi's management
accounts. The Group expects to publish a summary of unaudited financial
information for the quarter ended 31 December 2002 in respect of Marconi plc in
late February 2003.

Mike Parton, Chief Executive, said: "Despite slightly lower sales revenues all
our key financial performance measures have continued to improve. Costs have
fallen once again. We have generated operating cash in the quarter, margins are
higher than in the previous quarter and we are well on the way to returning to
operating profitability."

"These achievements, combined with progress towards our financial restructuring,
albeit slower than we would have liked, give us confidence for the future."


Trading Update

Overall conditions in the telecommunications market remained tough during the
third quarter. While signs of market stability have been observed in some areas
of the Europe, Middle East & Africa region (EMEA), particularly in Southern
Europe for example, the North American market was characterised by further
tightening of capital expenditure by a number of large telecom operators,
particularly towards the end of their financial years in December. In Central
and Latin America (CALA), the market was relatively stable during the quarter
although capital expenditure amongst major operators in the region remained at a
low level. In Asia-Pacific (APAC), while the market remains buoyant in
Australia, conditions in the Chinese market are more difficult as a result of
delays in capital expenditure due to the re-organisation of key customers,
delays to the roll-out of certain network build projects and increased pricing
pressure on new business.


Orders Received and Order Backlog

Core orders  received  increased by  approximately  8 per cent to GBP411 million
during the third quarter (Q2: GBP379 million). This was driven by an increase in
orders  received  for  Network  Services  largely as a result of two major order
extensions  awarded  during the  period,  both in the UK: an order  from  London
Underground  for the supply of further  communications  services for the Jubilee
Line and an order from BT relating to services for BT's narrowband network.

Core Book to Bill stood at 0.9 compared to 0.8 in the previous quarter. Book to
Bill in Network Equipment rose from 0.9 to 1.0 but the main driver of the
overall improvement was Network Services, which rose from 0.6 to 0.8, mainly as
a result of the new major orders booked during the period, described above.

Core order  backlog  stood at GBP761  million at 31 December  2002 (30 September
2002:  GBP916 million).  This decrease was mainly the result of the Group's exit
from its IT outsourcing services activity in North America (approximately GBP100
million). The balance of the decrease related mainly to the trading of long-term
service and support contracts particularly in the UK and Middle East.




Core Sales by Geography
in GBP million                                                  FY03

                                                   Q1            Q2           Q3
                                                                    

EMEA                                              285           285          287

US                                                153           142          127

APAC                                               47            45           29

CALA                                               25            10           13

Core                                              510           482          456



Third quarter Core sales decreased by GBP26 million or  approximately 5 per cent
to GBP456 million compared to the previous quarter.  This compared to Core sales
of GBP632 million in the third quarter of the previous  year,  representing a 28
per cent decline year on year.


On a sequential basis, modest increases in sales in EMEA and CALA were more than
offset by declines in the US and APAC.

In EMEA, sales increased by GBP2 million,  or approximately 1 per cent to GBP287
million  compared to the second  quarter.  Sales in the UK were flat compared to
the previous  quarter with lower sales of optical  networks  equipment offset by
increased sales of voice systems and customer support  services.  In Italy, Core
sales increased as a result of on-going  business under existing frame contracts
as operators continue to deploy core optical backbone and access networks. Sales
in Germany  fell  during the period as a result of further  capital  expenditure
cuts by the Group's wireline and wireless  network  customers and further delays
to  planned  third  generation  (3G)  mobile  network  rollouts  by  certain  3G
operators.

In the US,  sales fell  GBP15  million  or  approximately  11 per cent to GBP127
million  mainly as a result of the  continuing  tough market  conditions  in the
region and a decrease in sales of BBRS  equipment and services to the US Federal
Government  after the  seasonally  high level of sales  recorded in the previous
quarter.

In APAC, sales were down GBP16 million or 36 per cent to GBP29 million. The main
factor  contributing  to this  decline was the lower level of sales  recorded in
China as a result of the  delays in  capital  expenditure  and delays to certain
network  build  projects  by a number  of the  Group's  Chinese  customers.  The
reduction in sales also  reflects the  completion of the disposal of the Group's
wireless software and services  activities in the region in September 2002. This
business had accounted for GBP3 million of sales in the second quarter.

Sales  in CALA  increased  by GBP3  million,  or 30 per  cent to  GBP13  million
compared to the previous  quarter as a result of two specific new  contracts for
Broadband  Switching  equipment  in  Mexico  and  Brazil.  While  the  political
environment  in parts of the region  showed some signs of  stability  during the
period, generally conditions in the telecommunications market remain difficult.




Core Sales by Product Area
in GBP million                                                 FY03
                                                  Q1            Q2            Q3
                                                                    

Optical Networks                                 134           108            96

Broadband Routing and Switching (BBRS)            38            35            32

European Access                                   59            69            69

North American Access                             25            23            23

Outside Plant & Power (OPP)                       46            34            30

Other Network Equipment                           14            15            11

Network Equipment                                316           284           261

Installation, Commissioning &                     97            89            93

Maintenance (IC&M)

Value-Added Services (VAS)                        97           109           102

Network Services                                 194           198           195

Core                                             510           482           456



Sales of the Group's US-based  businesses  (defined as the equipment and service
activities of BBRS,  OPP and North American  Access)  amounted to GBP125 million
during the third quarter and are included in the Core sales  reported above (Q2:
GBP140 million).

Sales of Network  Equipment  dropped 8 per cent to GBP261  million  (Q2:  GBP284
million) mainly as a result of lower sales in Optical Networks and Other Network
Equipment. Sales of BBRS and OPP equipment fell compared to the previous quarter
while sales of Access systems in both Europe and North America  remained stable.
Network  Services  activities  were more  resilient,  particularly  where  those
services are not directly related to the provision of Network Equipment. Network
Services sales overall remained  relatively stable at GBP195 million (Q2: GBP198
million).

In Optical  Networks,  the 11 per cent  decline  to GBP96  million  (Q2:  GBP108
million)  was  predominantly  due to  lower  sales  in APAC as a  result  of the
difficult  market  conditions,  particularly in China described  above.  Optical
Networks sales in EMEA as a whole were stable  compared to the previous  quarter
with weaker demand for core transmission equipment from network operators in the
UK  offset  by  higher  sales in Italy and the  Middle  East.  During  the third
quarter,  SDH  accounted for 89 per cent of Optical  Networks  sales (Q2: 87 per
cent) and DWDM for 7 per cent (Q2: 11 per cent); the balance related to sales of
network  management  systems.  In January 2003, Marconi announced the award of a
new,  2-year frame contract with Telecom  Italia,  worth  approximately  Euro 15
million  (approximately  GBP10  million)  for the supply of an optical  backbone
network  architecture  based on the Group's  recently  launched next  generation
digital cross connect, the MSH2K.


Sales of BBRS equipment fell by 9 per cent to GBP32 million (Q2: GBP35 million).
Sales of BBRS services,  which for financial reporting purposes are consolidated
within  Network  Services,  fell by 25 per  cent to  GBP18  million  (Q2:  GBP24
million).  These  declines  were  mainly due to lower  volumes of  products  and
services  delivered to the US Federal  Government  following the seasonally high
level of sales in the  previous  quarter,  at the end of this  major  customer's
financial  year.  Sales to other  customers in North  America and EMEA  remained
stable compared to the previous quarter. Sales in APAC were lower as a result of
the difficult  market  conditions in the region while sales in CALA saw a modest
increase due to two specific contracts with Telefonica  (Brazil) and the Mexican
Supreme Court.  In December 2002,  Marconi  announced the first European sale of
its recently  launched  multi-service  core  switch-router,  the BXR 48000, to a
major financial institution.

European  Access sales  remained  stable at GBP69 million (Q2:  GBP69  million).
Sales of the Group's fixed wireless access systems in Germany were down compared
to the previous  quarter as a result of reduced capital  expenditure by a number
of the major German  wireless  operators.  This decrease was offset by increased
sales of voice  systems in the UK largely due to a software  upgrade and of high
density DSLAMs (Access Hub) in Italy and CALA. During the third quarter, Marconi
announced the first sale of its recently  launched  Softswitch  system to Jersey
Telecom.  On 8 January  2003,  Marconi  announced a new order for its Access Hub
platform from French competitive network operator, LDCOM.

North American  Access sales were stable at GBP23 million (Q2:  GBP23  million).
Bell South remains the largest  customer of access equipment in North America as
it  continues  to roll  out the  Group's  copper  access  and  fiber-to-the-curb
solutions.

Sales of OPP equipment  fell 12 per cent to GBP30 million (Q2:  GBP34  million).
Sales of OPP services,  which for financial  reporting purposes are consolidated
within Network  Services,  fell 8 per cent to GBP22 million (Q2: GBP24 million).
These  declines  were in line with the  overall  trend in the market for outside
plant and power  equipment  and services in the Americas and the Group  believes
that it continues to maintain its strong market positions in this business.

Other Network Equipment sales fell by GBP4 million, or approximately 27 per cent
to GBP11  million (Q2:  GBP15  million).  This decline  occurred in APAC and was
mainly due to the  completion  of a one-off  contract  in the region  during the
previous quarter.

IC&M sales  increased  by GBP4  million,  or  approximately  4 per cent to GBP93
million (Q2: GBP89 million). Sales increased in the UK partly as a result of the
Group's  focus  on  reducing  the  time  between  equipment  provision  and  its
installation and  commissioning.  These were partially offset by the decrease in
OPP service sales in the US described above.

VAS sales dropped by GBP7 million, or approximately 6 per cent to GBP102 million
(Q2:  GBP109  million).  This  was  mainly  due to lower  sales of  BBRS-related
services to the US Federal  Government,  in  particular,  in relation to a major
airport  services  contract  which is near to completion and also as a result of
lower  sales of IT  outsourcing  services  prior to the  Group's  exit from this
activity,  which was completed during December 2002. Sales of Integrated Systems
and Wireless Services were relatively stable compared to the previous quarter.

Key Customers

Marconi continued to benefit from the support of its strong customer base of
predominantly incumbent operators and government agencies during the third
quarter. The majority of Core sales in the period were derived from existing
frame contracts.

The ten largest customers during the third quarter were BellSouth, BT, Ericsson,
Metro City Carriers, Telecom Italia, Telkom South Africa, UK Government, US
Federal Government, Verizon and Vodafone Group. In aggregate, these customers
accounted for 46 per cent of third quarter Core sales (Q2: ten largest customers
48 per cent). BT remains the Group's largest customer and accounted for 19 per
cent of Core sales in the third quarter (Q2: 19 per cent).

Operating Performance

Despite the lower sales volumes, Core gross margin showed a small improvement
compared to the underlying margin before stock provisions recorded in the
previous quarter (Q2: 21.6 per cent of sales). This improvement was mainly
achieved through further cost savings in the supply chain and within the Group's
service activities. While the accounting processes for the third quarter are not
yet complete, the Group does not currently expect to raise additional stock
provisions for the reporting period.

Further  progress was made towards  achieving the Group's  target to reduce Core
operating  costs to an annualised  run-rate of GBP520  million by the end of the
current  financial  year. At the end of the third  quarter,  the operating  cost
run-rate had fallen to approximately GBP550 million compared to an exit run-rate
of GBP635  million at the end of the previous  quarter.  Savings  were  achieved
across all main categories of expenditure - research and development,  sales and
marketing and general and administrative. The majority of these savings resulted
from  headcount  reductions.  Also during the quarter,  further  cost  reduction
actions were  initiated  and the Group  remains on track to achieve its targeted
GBP450  million  annualised  operating  cost run-rate  during the financial year
ending 31 March 2004.

Core  headcount  has  been  reduced  by  approximately  3,000  since  the end of
September  2002 and, at the end of December  2002 was just over  16,000.  Of the
total number of leavers during the period,  approximately 500 employees left the
Group  as a  result  of  the  disposal  of  the  Group's  South  African  legacy
operations, ATC, completed during December 2002.

A further 1,400 leavers have been  identified and announced and are due to leave
the business in the next few months,  giving a known headcount  target of around
14,600.  Once the reduced  operating  cost target has been  achieved,  the Group
expects to employ  around  14,000  people in its Core  business.  As  previously
disclosed,  the Group will continue to incur  exceptional cash costs in order to
complete its planned headcount reductions.

The overall operating performance in the Core business improved substantially
compared to the previous quarters of the financial year as a result of the
increase in Core gross margin and the further operating cost savings achieved
during the period.

Cash / Net Debt

Further significant progress was made towards the Group's goal to reach a
sustainable operating cash breakeven position. The Group recorded a positive
operating cash flow during the quarter, largely as a result of the improved
operating performance and reductions in working capital compared to the previous
quarter. Non-operating cash outflows relating to the Group's ongoing headcount
reduction programme and interest paid were partially offset by a tax refund
received during the period. In total, the Group's cash balance remained broadly
stable compared to the position at the end of September 2002.

At 31 December 2002,  net debt amounted to GBP2.8  billion and comprised  GBP3.9
billion of gross  financial debt made up of GBP1.7 billion of Euro and US dollar
bond debt,  GBP2.1  billion of  Syndicate  Bank debt  (including  GBP30  million
relating to the conversion of interest swap and equity  derivative  arrangements
to new loan  agreements  during  the  quarter  and  GBP54  million  relating  to
conversion  of  interest  swap  arrangements  during the first  half) and GBP0.1
billion of bilateral  and other bank debt offset by GBP1.1  billion of cash.  No
account has been taken of the impact of the proposed Restructuring.



Financial Restructuring

On 16 December 2002, Marconi announced modifications to the non-binding
indicative Heads of Terms for the financial restructuring of Marconi plc and its
wholly-owned subsidiary Marconi Corporation plc (the "Restructuring") and
amendments to the Interim Security provided to the Group's Syndicate Banks and
bondholders (including the bond trustees) and certain ESOP derivative providers.
Since that announcement, Marconi has made substantial progress in finalising
both the Scheme documentation which will be despatched to Scheme Creditors and
the Prospectus in connection with the listing of Marconi Corporation on the
London Stock Exchange.


Since 16 December 2002, the commercial terms outlined in the announcement have
been reflected in the restructuring documentation, which is now substantially
complete. In addition, the mechanics for enabling the Senior Notes to be
denominated in Euros with a possible US dollar option within certain limitations
have now been clarified and will enable creditors, at their option, to elect for
Senior Notes denominated in Euros or US$ within certain limitations.
Furthermore, negotiations to finalise the terms of the GBP50 million super
priority performance bonding facility and Marconi's working capital facilities
in the USA are also progressing well.

While significant progress has been made in preparing the documentation
necessary for the Restructuring, the expectation stated in December that the
formal Scheme documentation would be posted to Scheme Creditors in January 2003
with an effective date on or before 15 March, 2003 has now proved to be
unachievable. Given the complexity of the arrangements being documented, Marconi
now believes that finalisation of the documentation should be achieved within
the next few weeks with Scheme documentation being posted to creditors towards
the end of February following the initial court hearing. It is now expected that
implementation of the Restructuring will take place in April.

Marconi  still  expects to  complete  the  Restructuring  in line with the terms
announced on 29 August, 2002 as amended by the announcement on 16 December 2002.
The  Group  remains  on track to  distribute  GBP260  million  in cash to Scheme
creditors, of which GBP95 million has already been paid to financial creditors.

Marconi's Board continues to believe the proposed Restructuring is in the best
interests of Marconi and its stakeholders as a whole. The Board believes that it
will continue to receive the support of the joint lead co-ordinators of the
Syndicate Banks and the informal ad hoc committee of bondholders in finalising
the documentation to effect the Restructuring. The Board will be communicating
with the Syndicate Banks and the informal ad hoc committee of bondholders to
obtain the support of the creditor groups for an extension to the timetable.

Definitions


        1)     Operating cash flow is defined as cash flow from continuing
               operations before net capital expenditure and exceptional items

        2)     Operating costs are defined as research and development costs,
               general and administrative costs, selling and distribution costs
               and other costs but excluding goodwill amortisation and
               exceptional items

ENDS/...



Notes to Editors

About Marconi plc

Marconi plc is a global telecommunications equipment and solutions company
headquartered in London. The company's core business is the provision of
innovative and reliable optical networks, broadband routing and switching and
broadband access technologies and services. The company's customer base includes
many of the world's largest telecommunications operators.

The company is listed on the London Stock Exchange under the symbol MONI.
Additional information about Marconi can be found at www.marconi.com.

Copyright (c) 2002 Marconi plc. All rights reserved. All brands or product names
are trademarks of their respective holders.

Contacts

Name: David Beck / Joe Kelly                  Heather Green

Title: Public Relations                       Investor Relations

Phone: +44 (0) 207 306 1771                   +44 (0) 207 306 1735
+44 (0) 207 603 1490
joe.kelly@marconi.com                         heather.green@marconi.com



Cautionary statement regarding forward-looking statements

In order to utilize the "Safe Harbor" provision of the U.S. Private Securities
Litigation Reform Act of 1995, Marconi plc ("the Company") is providing the
following cautionary statement. Except for reported financial results or other
historical information, certain statements in this press release are
forward-looking statements, including, but not limited to, statements that are
predictions of or indicate future events, trends, plans or objectives. Reliance
should not be placed on such statements because, by their nature, they are
subject to known and unknown risks and uncertainties and can be affected by
other factors which are beyond the control of the Company and its subsidiaries,
and may cause actual results, performance and achievements to differ materially
from anticipated future results, performance and achievements expressed or
implied in the forward-looking statements (and from the past results,
performance or achievement). Although not exhaustive, the following factors
could cause such differences: any major disruption in production at our key
facilities; changes in the environmental, tax and other laws and regulations,
which, among other things, could cause us to incur substantial additional
capital expenditures and operation and maintenance costs; and adverse changes in
the markets for our products, including as a result of increased competition in
the highly competitive international markets for such products. These factors
and other factors that could effect these forward-looking statements are
described in the Company's Form 20-F report and Form 6-K reports filed with the
U.S. Securities and Exchange Commission. The Company disclaims any obligation to
publicly update or revise these forward-looking statements, whether to reflect
new information or future events or circumstances or otherwise.



                                   SIGNATURES

Pursuant  to the  requirements  of the  Securities  Exchange  Act of  1934,  the
registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
undersigned, thereunto duly authorized.


                                       MARCONI PLC



                                       By:     ____M Skelly____

                                       Name:   M Skelly
                                       Title:  Secretary


Date: 24 January 2003