The Sunningdale Agreement was an attempt to establish a power-sharing Northern Ireland Executive and a cross-border Council of Ireland. The agreement was signed by the British and Irish governments at Northcote House in Sunningdale Park, located in Sunningdale, Berkshire, on 9 December 1973. Unionist opposition, violence and a general strike caused the collapse of the agreement in May 1974.

Sunningdale is a large village with a retail area and a civil parish in the Royal Borough of Windsor and Maidenhead. It takes up the extreme south-east corner of Berkshire, England. It has a railway station on the (London) Waterloo to Reading Line and is adjoined by green buffers including Sunningdale Golf Club and Wentworth Golf Club. Its northern peripheral estates adjoin Virginia Water Lake.