Notifiable Interest

Costain Group PLC
09 December 2004

Costain Group PLC

(the 'Company')



Notifiable Interest



Costain announces that it has been notified on 9 December 2004 that Artemis UK
Growth Fund ('Artemis') holds 13,200,000 ordinary shares in the Company
equivalent to 3.74% of the issued share capital. The date on which the
transaction was effected is not known.





                                                                 9 December 2004

Enquiries:



Costain Group PLC            Tel: [phone]         [e-mail]
Clive L Franks



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