Block Listing

Costain Group PLC
19 May 2006





Costain Group plc





BLOCK LISTING SIX MONTHLY RETURN




Name of applicant:                                         COSTAIN GROUP PLC

Name of scheme:                                            Costain Group PLC Savings-Related Share Option Scheme

Period of return:                          From:           22 November 2005      To:       19 May 2006

Balance under scheme from previous return:                 4,147,605 shares

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

Number of securities issued/allotted under scheme during   3,643,774 shares
period:

Balance under scheme not yet issued/allotted at end of     503,831 shares
period

Number and class of securities originally listed and the   4,147,605 ordinary 5p shares (22 November 2005)
date of admission

Total number of securities in issue at the end of the      357,205,376 ordinary 5p shares
period


Name of contact:                                           Clive Franks

Address of contact:                                        Costain House, Nicholsons Walk, Maidenhead, Berkshire,
                                                           SL6 1LN

Telephone number of contact:                               01628 842575



                                                                     22 May 2006


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