Share of interest

Costain Group PLC
01 February 2007



TR-1(i): NOTIFICATION OF MAJOR INTERESTS IN SHARES



1. Identity of the issuer or the underlying issuer of existing shares to which
voting rights are attached (ii):

Costain Group PLC



2. Reason for the notification (please state Yes/No): (    )



An acquisition or disposal of voting rights: ( Yes  )



An acquisition or disposal of financial instruments which may result in the
acquisition of shares already issued to which voting rights are attached: (    )



An event changing the breakdown of voting rights: (    )



Other (please specify) : (    )



3. Full name of person(s) subject to the notification obligation (iii):

Saad Shehata



4. Full name of shareholder(s) (if different from 3.) (iv):

Mohammed Abdulmohsin Al-Kharafi & Sons WLL



5. Date of the transaction (and date on which the threshold is crossed or
reached if different) (v):

31 January 2007



6. Date on which issuer notified:

1 February 2007



7. Threshold(s) that is/are crossed or reached:

22%



8. Notified details:







A: Voting rights attached to shares


Class/type of shares if possible           Situation previous to the Triggering transaction (vi)
using the ISIN CODE
                                  Number of shares                   Number of voting Rights (viii)


GB0002272184                      0                                  0





Resulting situation after the triggering transaction (vii)


Class/type of shares if      Number of shares         Number of voting rights (ix)      % of voting rights
possible using the ISIN CODE
                             Direct                   Direct (x)   Indirect (xi)        Direct      Indirect


                             79,168,523               0            79,168,523           0           22



B: Financial Instruments

Resulting situation after the triggering transaction (xii)


Type of         Expiration Date       Exercise/Conversion       Number of voting rights     % of voting rights
financial       (xiii)                Period/ Date (xiv)        that may be acquired if the
instrument                                                      instrument is exercised/
                                                                converted.








Total (A+B)
Number of voting rights        % of voting rights


79,168,523                     22



9. Chain of controlled undertakings through which the voting rights and/or the
financial instruments are effectively held, if applicable (xv):





Proxy Voting:



10. Name of the proxy holder:

Saad Shehata



11. Number of voting rights proxy holder will cease to hold:

79,168,523 (22%)



12. Date on which proxy holder will cease to hold voting rights:

2 February 2007



13. Additional information:

When proxy expires 22% of voting rights will return to Mohammed Abdulmohsin
Al-Kharafi & Sons WLL





14. Contact name:

Saad Shehata



15. Contact telephone number:

00202 5746681


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