Scrip Dividend Scheme

Costain Group PLC

("Costain" or "the Company")

Scrip Dividend Scheme

The scrip dividend calculation price for the 2010 interim dividend payable on 29 October 2010 is 217.35p. This is the reference price at which Costain Group PLC ordinary shares will be issued to shareholders who have elected to take shares in lieu of cash dividends through participation in the Costain Scrip Dividend Scheme. This price is based on the average of the middle market quotations of Costain Group PLC ordinary shares derived from the London Stock Exchange Daily Official List for the five consecutive business days 22-24 and 27-28 September 2010 inclusive.

Any shareholders entitled to the 2010 interim dividend who do not already participate in the Costain Scrip Dividend Scheme and wish to do so, should contact the Company's Registrar, Equiniti, on 0871 384 2268 to obtain a mandate form. This form must be returned to Equiniti to arrive by no later than 5pm on 8 October 2010 in order for it to be effective for the 2010 interim dividend.

1 October 2010

Enquiries: