Costain Group PLC

30 March 2023

LONG TERM INCENTIVE PLAN - LISTING APPLICATION

Application has been made for the admission ("Admission") of 1,600,000 new ordinary shares of 50p each in the Company (the "Shares") to the Official List of the UK Listing Authority and to trading on the London Stock Exchange's market for listed securities.

Admission is subject to the allotment of shares by the Company relating to the vesting of share options that were granted under the Company's Long Term Incentive Plan in October and November 2020.

The Shares will be issued fully paid and will, upon issue, rank pari passu in all respects with the Company's existing issued shares. Admission, subject to allotment, is expected to occur on 4 April 2023.

ENQUIRIES

Investors and analysts

Paul Sharma, Costain                                     +44 (0)7867 501188

Financial media - Headland                        costain@headlandconsultancy.com

Andy Rivett-Carnac                                       +44 (0)7968 997365

Charlie Twigg                                                 +44 (0)7946 494568