Additional Listing

Spirent PLC
31 March 2004

                                                                   31 March 2004

                                  SPIRENT PLC

 ADDITIONAL LISTING OF ORDINARY SHARES IN RESPECT OF DEFERRED CONSIDERATION FOR
                     THE ACQUISITION OF CAW NETWORKS, INC.


Spirent plc (LSE: SPT; NYSE: SPM), a leading communications technology company,
today announced it would be issuing 4,352,742 Ordinary shares of 3 1/3 pence
each (Ordinary shares) in respect of the deferred consideration for the
acquisition of Caw Networks, Inc. (Caw) following the achievement of certain
technical and financial milestones by Caw.

On 16 August 2002, Spirent completed the acquisition of Caw for an initial cash
consideration of $49 million. As part of the acquisition, there was an element
of deferred consideration which was dependent on certain technical and financial
milestones being met. As previously reported on 25 February 2004 in the
Company's 2003 preliminary results statement, Caw has achieved a certain level
of the earn-out targets. The amount of deferred consideration due is $10 million
which the Company has elected to satisfy by the issue of 4,352,742 Ordinary
shares with reference to an Ordinary share price of 120 pence in accordance with
the terms of the Caw acquisition agreement. Dealings in these Ordinary shares
are expected to commence on 31 March 2004.

Accordingly, application has been made to the UK Listing Authority for the
Ordinary shares being issued to be admitted to the Official List and to the
London Stock Exchange for the Ordinary shares to be admitted to trading with
effect from 31 March 2004. The Ordinary shares shall rank pari passu with the
existing issued Ordinary shares of the Company.

                                    - ends -


Enquiries

Nicholas Brookes, Chief Executive         Spirent plc         [phone]
Eric Hutchinson, Finance Director

Investor Relations
Catherine Nash                            Spirent plc         [phone]


About Spirent

Spirent is a leading communications technology company focused on delivering
innovative systems and services to meet the needs of customers worldwide.  We
are a global provider of performance analysis and service assurance solutions
that enable the development and deployment of next-generation networking
technologies such as broadband services, Internet telephony, 3G wireless and web
applications and security testing.  Our Network Products business is a developer
and manufacturer of innovative solutions for fastening, identification,
protection and connectivity in electrical and communications networks marketed
under the global brand HellermannTyton.  The Systems group comprises PG Drives
Technology, which develops power control systems for specialist electrical
vehicles in the mobility and industrial markets, and an aerospace business that
provides ground-based logistics support software systems for the aviation
market.  Further information about Spirent plc can be found at www.spirent.com

Spirent Ordinary shares are traded on the London Stock Exchange (ticker: SPT)
and on the New York Stock Exchange (ticker: SPM; CUSIP number: 84856M209) in the
form of American Depositary Shares (ADS), represented by American Depositary
Receipts, with one ADS representing four Ordinary shares.

Spirent and the Spirent logo are registered trademarks of Spirent plc.  All
rights reserved.

This press release may contain forward-looking statements that are based on
current expectations or beliefs, as well as assumptions about future events.  By
their nature, forward-looking statements are inherently predictive, speculative
and involve risk and uncertainty because they relate to events and depend on
circumstances that will occur in the future.  You should not place undue
reliance on these forward-looking statements, which are not a guarantee of
future performance and are subject to factors that could cause our actual
results to differ materially from those expressed or implied by these
statements.  These risks include the risks described from time to time in
Spirent plc's Securities and Exchange Commission periodic reports and filings.
The Company undertakes no obligation to update any forward-looking statements
contained in this press release, whether as a result of new information, future
events or otherwise.


                      This information is provided by RNS
            The company news service from the London Stock Exchange