Leighton contested Middleton and Prestwich at the 1964 general election, but was beaten by the Conservative incumbent Sir John Barlow.
At the February 1974 election he fought the new Horsham and Crawley seat, but was defeated by the Conservative Peter Hordern.
He became an MP in 1979 by regaining Newham North East for his party; it had been the seat of Reg Prentice, who during the previous Parliament had defected from Labour to the Conservatives.
Leighton was opposed to British membership of the European Communities, and was Director of the Common Market Safeguards Campaign from 1970 to 1972.
(Coincidentally, the MP for neighbouring Barking, Jo Richardson, also died in the same month, resulting in by-elections being held on the same day for both seats).