Blocklisting Interim Review

Spirent PLC
06 January 2006


                           BLOCKLISTING SIX MONTHLY RETURN


To:       The FSA


Date: 6 January 2006



Name of applicant:                SPIRENT PLC

Name of scheme:                   SPIRENT EXECUTIVE SHARE OPTION SCHEME

Period of return:                 From: 1 JULY 2005               To: 31 DECEMBER 2005

Balance under scheme from previous return:            2,801,274 ORDINARY SHARES OF 3 1/3p EACH

The amount by which the block scheme has been         NIL
increased, if the scheme has been increased since the
date of the last return:


Number of securities issued/allotted under scheme     415,240 ORDINARY SHARES OF 3 1/3p EACH
during period:

Balance under scheme not yet issued/allotted at end   2,386,034 ORDINARY SHARES OF 3 1/3p EACH
of period:

Number and class of securities originally listed and  3,000,000 ORDINARY SHARES OF 3 1/3p EACH DATED 29
the date of admission:                                SEPTEMBER 2000


                                                      3,000,000 ORDINARY SHARES OF 3 1/3 p EACH DATED 28
                                                      MAY 2004


Total number of securities in issue at the end of the 965,789,582
period :


Name of contact:                                        Michael Anscombe

Address of contact:                                     Spirent plc

                                                        Spirent House

                                                        Crawley Business Quarter

                                                        Fleming Way

                                                        Crawley, RH10 9QL

Telephone number of contact:                            01293 767676



SIGNED BY       M Anscombe, Assistant Company Secretary_________________________

Director/company secretary/suitably experienced employee/duly authorised
officer, for and on behalf of

 
Spirent plc_______________________________________________

Name of applicant



 If you knowingly or recklessly give false or misleading information you may be
                             liable to prosecution.


                         BLOCKLISTING SIX MONTHLY RETURN

To:       The FSA


Date: 6 January 2006



Name of applicant:                SPIRENT PLC

Name of scheme:                   U.S EMPLOYEE STOCK PURCHASE PLAN

Period of return:                 From: 1 JULY 2005               To: 31 DECEMBER 2005

Balance under scheme from previous return:            1,237,364 ORDINARY SHARES OF 3 1/3p EACH

The amount by which the block scheme has been         NIL
increased, if the scheme has been increased since the
date of the last return:


Number of securities issued/allotted under scheme     NIL
during period:

Balance under scheme not yet issued/allotted at end   1,237,364 ORDINARY SHARES OF 3 1/3p EACH
of period:

Number and class of securities originally listed and  3,000,000 ORDINARY SHARES OF 3 1/3p EACH DATED 29
the date of admission:                                SEPTEMBER 2000


                                                      3,000,000 ORDINARY SHARES OF 3 1/3 p EACH DATED 28
                                                      MAY 2004


Total number of securities in issue at the end of the 965,789,582
period :


Name of contact:                                        Michael Anscombe

Address of contact:                                     Spirent plc

                                                        Spirent House

                                                        Crawley Business Quarter

                                                        Fleming Way

                                                        Crawley, RH10 9QL

Telephone number of contact:                            01293 767676



SIGNED BY       M Anscombe, Assistant Company Secretary_________________________

Director/company secretary/suitably experienced employee/duly authorised
officer, for and on behalf of


Spirent plc_______________________________________________

Name of applicant



 If you knowingly or recklessly give false or misleading information you may be
                             liable to prosecution.


                       BLOCKLISTING SIX MONTHLY RETURN


To:       The FSA


Date: 6 January 2006


Name of applicant:                SPIRENT PLC

Name of scheme:                   SPIRENT GLOBAL ALL EMPLOYEE SHARE PURCHASE PLAN

Period of return:                 From: 1 JULY 2005               To: 31 DECEMBER 2005

Balance under scheme from previous return:            814,444 ORDINARY SHARES OF 3 1/3p EACH

The amount by which the block scheme has been         NIL
increased, if the scheme has been increased since the
date of the last return:


Number of securities issued/allotted under scheme     NIL
during period:

Balance under scheme not yet issued/allotted at end   814,444 ORDINARY SHARES OF 3 1/3p EACH
of period:

Number and class of securities originally listed and  3,000,000 ORDINARY SHARES OF 3 1/3p EACH DATED 29
the date of admission:                                SEPTEMBER 2000


                                                      3,000,000 ORDINARY SHARES OF 3 1/3 p EACH DATED 28
                                                      MAY 2004


Total number of securities in issue at the end of the 965,789,582
period :


Name of contact:                                        Michael Anscombe

Address of contact:                                     Spirent plc

                                                        Spirent House

                                                        Crawley Business Quarter

                                                        Fleming Way

                                                        Crawley, RH10 9QL

Telephone number of contact:                            01293 767676


SIGNED BY       M Anscombe, Assistant Company Secretary_________________________

Director/company secretary/suitably experienced employee/duly authorised
officer, for and on behalf of


Spirent plc_______________________________________________

Name of applicant



 If you knowingly or recklessly give false or misleading information you may be
                             liable to prosecution.


                              BLOCKLISTING SIX MONTHLY RETURN


To:       The FSA


Date: 6 January 2006


Name of applicant:                SPIRENT PLC

Name of scheme:                   NETCOM AMENDED AND RESTATED STOCK OPTION PLAN

Period of return:                 From: 1 JULY 2005               To: 31 DECEMBER 2005

Balance under scheme from previous return:            4,369,664 ORDINARY SHARES OF 3 1/3p EACH

The amount by which the block scheme has been         NIL
increased, if the scheme has been increased since the
date of the last return:


Number of securities issued/allotted under scheme     168,770 ORDINARY SHARES OF 3 1/3p EACH
during period:

Balance under scheme not yet issued/allotted at end   4,200,894 ORDINARY SHARES OF 3 1/3p EACH
of period:

Number and class of securities originally listed and  3,000,000 ORDINARY SHARES OF 3 1/3p EACH DATED 29
the date of admission:                                SEPTEMBER 2000


                                                      3,000,000 ORDINARY SHARES OF 3 1/3 p EACH DATED 28
                                                      MAY 2004


Total number of securities in issue at the end of the 965,789,582
period :


Name of contact:                                        Michael Anscombe

Address of contact:                                     Spirent plc

                                                        Spirent House

                                                        Crawley Business Quarter

                                                        Fleming Way

                                                        Crawley, RH10 9QL

Telephone number of contact:                            01293 767676


SIGNED BY       M Anscombe, Assistant Company Secretary_________________________

Director/company secretary/suitably experienced employee/duly authorised
officer, for and on behalf of


Spirent plc_______________________________________________

Name of applicant


 If you knowingly or recklessly give false or misleading information you may be
                             liable to prosecution.


                           BLOCKLISTING SIX MONTHLY RETURN

To:       The FSA


Date: 6 January 2006



Name of applicant:                SPIRENT PLC

Name of scheme:                   ZARAK AMENDED AND RESTATED STOCK OPTION PLAN

Period of return:                 From: 1 JULY 2005               To: 31 DECEMBER 2005

Balance under scheme from previous return:            2,690,996 ORDINARY SHARES OF 3 1/3p EACH

The amount by which the block scheme has been         NIL
increased, if the scheme has been increased since the
date of the last return:


Number of securities issued/allotted under scheme     NIL
during period:

Balance under scheme not yet issued/allotted at end   2,690,996 ORDINARY SHARES OF 3 1/3p EACH
of period:

Number and class of securities originally listed and  3,000,000 ORDINARY SHARES OF 3 1/3p EACH DATED 29
the date of admission:                                SEPTEMBER 2000


                                                      3,000,000 ORDINARY SHARES OF 3 1/3 p EACH DATED 28
                                                      MAY 2004


Total number of securities in issue at the end of the 965,789,582
period :


Name of contact:                                        Michael Anscombe

Address of contact:                                     Spirent plc

                                                        Spirent House

                                                        Crawley Business Quarter

                                                        Fleming Way

                                                        Crawley, RH10 9QL

Telephone number of contact:                            01293 767676


SIGNED BY       M Anscombe, Assistant Company Secretary_________________________

Director/company secretary/suitably experienced employee/duly authorised
officer, for and on behalf of


Spirent plc_______________________________________________

Name of applicant



 If you knowingly or recklessly give false or misleading information you may be
                             liable to prosecution.


                              BLOCKLISTING SIX MONTHLY RETURN

To:       The FSA


Date: 6 January 2006



Name of applicant:                SPIRENT PLC

Name of scheme:                   SPIRENT SAVINGS RELATED SHARE OPTION SCHEME

Period of return:                 From: 1 JULY 2005               To: 31 DECEMBER 2005

Balance under scheme from previous return:            114,388 ORDINARY SHARES OF 3 1/3p EACH

The amount by which the block scheme has been         NIL
increased, if the scheme has been increased since the
date of the last return:


Number of securities issued/allotted under scheme     46,203 ORDINARY SHARES OF 3 1/3p EACH
during period:

Balance under scheme not yet issued/allotted at end   68,185 ORDINARY SHARES OF 3 1/3p EACH
of period:

Number and class of securities originally listed and  3,000,000 ORDINARY SHARES OF 3 1/3p EACH DATED 29
the date of admission:                                SEPTEMBER 2000


                                                      3,000,000 ORDINARY SHARES OF 3 1/3 p EACH DATED 28
                                                      MAY 2004


Total number of securities in issue at the end of the 965,789,582
period :


Name of contact:                                        Michael Anscombe

Address of contact:                                     Spirent plc

                                                        Spirent House

                                                        Crawley Business Quarter

                                                        Fleming Way

                                                        Crawley, RH10 9QL

Telephone number of contact:                            01293 767676



SIGNED BY       M Anscombe, Assistant Company Secretary_________________________

Director/company secretary/suitably experienced employee/duly authorised
officer, for and on behalf of


Spirent plc_______________________________________________

Name of applicant



 If you knowingly or recklessly give false or misleading information you may be
                             liable to prosecution.


                             BLOCKLISTING SIX MONTHLY RETURN

To:       The FSA


Date: 6 January 2006


Name of applicant:                SPIRENT PLC

Name of scheme:                   SPIRENT STOCK INCENTIVE PLAN

Period of return:                 From: 1 JULY 2005               To: 31 DECEMBER 2005

Balance under scheme from previous return:            5,509,645 ORDINARY SHARES OF 3 1/3p EACH

The amount by which the block scheme has been         NIL
increased, if the scheme has been increased since the
date of the last return:


Number of securities issued/allotted under scheme     1,055,959 ORDINARY SHARES OF 3 1/3p EACH
during period:

Balance under scheme not yet issued/allotted at end   4,453,686 ORDINARY SHARES OF 3 1/3p EACH
of period:

Number and class of securities originally listed and  3,000,000 ORDINARY SHARES OF 3 1/3p EACH DATED 29
the date of admission:                                SEPTEMBER 2000


                                                      3,000,000 ORDINARY SHARES OF 3 1/3 p EACH DATED 28
                                                      MAY 2004


Total number of securities in issue at the end of the 965,789,582
period :


Name of contact:                                        Michael Anscombe

Address of contact:                                     Spirent plc

                                                        Spirent House

                                                        Crawley Business Quarter

                                                        Fleming Way

                                                        Crawley, RH10 9QL

Telephone number of contact:                            01293 767676


SIGNED BY       M Anscombe, Assistant Company Secretary_________________________

Director/company secretary/suitably experienced employee/duly authorised
officer, for and on behalf of


Spirent plc_______________________________________________

Name of applicant



 If you knowingly or recklessly give false or misleading information you may be
                             liable to prosecution.


                           BLOCKLISTING SIX MONTHLY RETURN

To:       The FSA


Date: 6 January 2006


Name of applicant:                SPIRENT PLC

Name of scheme:                   CAW AMENDED AND RESTATED STOCK OPTION PLAN

Period of return:                 From: 1 JULY 2005               To: 31 DECEMBER 2005

Balance under scheme from previous return:            855,550 ORDINARY SHARES OF 3 1/3p EACH

The amount by which the block scheme has been         NIL
increased, if the scheme has been increased since the
date of the last return:


Number of securities issued/allotted under scheme     19,151 ORDINARY SHARES OF 3 1/3p EACH
during period:

Balance under scheme not yet issued/allotted at end   836,399 ORDINARY SHARES OF 3 1/3p EACH
of period:

Number and class of securities originally listed and  3,000,000 ORDINARY SHARES OF 3 1/3p EACH DATED 29
the date of admission:                                SEPTEMBER 2000


                                                      3,000,000 ORDINARY SHARES OF 3 1/3 p EACH DATED 28
                                                      MAY 2004


Total number of securities in issue at the end of the 965,789,582
period :


Name of contact:                                        Michael Anscombe

Address of contact:                                     Spirent plc

                                                        Spirent House

                                                        Crawley Business Quarter

                                                        Fleming Way

                                                        Crawley, RH10 9QL

Telephone number of contact:                            01293 767676


SIGNED BY       M Anscombe, Assistant Company Secretary_________________________

Director/company secretary/suitably experienced employee/duly authorised
officer, for and on behalf of


Spirent plc_______________________________________________

Name of applicant


If you knowingly or recklessly give false or misleading information you may be
liable to prosecution.


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