His majority of 57 votes, taking the seat from the Conservatives, was the narrowest by-election result since Carmarthen in 1926 which the Liberals held by 47 votes. The by-election was called following the resignation of Conservative MP Lord Lambton, Parliamentary Under Secretary of State for Defence, after he was involved in a sex scandal. Lambton resigned in July 1973 and the Liberal Party used the time effectively, appointing one of its top agents, John Spiller, to nurse the constituency. In Beith, the party had a well known and popular candidate. He was a local councillor and had contested Berwick in 1970. Although a gain the result was much narrower than expected and was something of a disappointment. Despite his slim majority, Beith held the seat until he retired in 2015.