Update on AGM Political Donations Resolution Vote

At the Company's AGM held on 14 May 2026, resolution 14, which sought authorisation to make political donations or expenditure, passed with the requisite majority of votes. However, 20.57% of the votes cast were against the resolution. This announcement is made in accordance with Provision 4 of the UK Corporate Governance Code and provides an update to the Company's Result of AGM announcement published on 14 May 2026. Following the AGM, Costain discussed the resolution with the Company's largest shareholders who voted against the resolution. Those discussions indicated that their voting position reflected the shareholders' general policy position on political donations/expenditure, rather than any concerns regarding the Company.

Consistent with the approach adopted by many UK listed companies, Costain intends to continue seeking annual renewal of this authority as a precautionary measure. This is because the very broad definitions of "political donations" and "political expenditure" under the Companies Act 2006 may capture certain routine business activities that would not ordinarily be regarded as political in nature. The Company's policy is, and continues to be, to not make political donations or to incur political expenditure.

The Board recognises the importance of maintaining effective communication with shareholders and remains committed to constructive engagement with both institutional and private shareholders on this matter.