Holding(s) in Company

Costain Group PLC
09 May 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):

David Jefferies



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

Shareholder interests below 3%



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

8 May 2007



6. Date on which issuer notified:

9 May 2007



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

12%



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                      225,000                            225,000





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


                             45,951,773               225,000      45,726,773           0.063       12.8



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.


N/A





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


45,951,773                     12%



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

N/A



Proxy Voting:



10. Name of the proxy holder:

David Jefferies



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

45,726,773



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

10 May 2007



13. Additional information:

When proxy expires 12.8% of voting rights will return to the shareholders that
appointed David Jefferies as their proxy.



14. Contact name:

David Jefferies



15. Contact telephone number:

01628 842 121





Annex to Notification Of Major Interests In Shares (xvi)



A: Identity of the person or legal entity subject to the notification obligation



Full name (including legal form for legal entities):

David Jefferies



Contact address (registered office for legal entities):

Costain House, Nicholsons Walk, Maidenhead, Berkshire, SL6 1LN



Phone number:

01628 842 121



Other useful information (at least legal representative for legal persons):

.................






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