At the 1964 general election, John Selwyn Gummer stood as a candidate in the Greenwich constituency, but was heavily defeated by the incumbent Labour MP, Richard Marsh. He stood again some 18 months later at the 1966 general election and lost even more heavily.
He was finally elected to the House of Commons on his third attempt, at the 1970 general election, when he narrowly unseated the sitting MP James Dickens in the Lewisham West constituency. However, at the February 1974 general election he lost the seat to Labour's Christopher Price, and failed to regain it in the October 1974 election.
In 1979, he eventually returned to the House of Commons, securing the seat of Eye, following the retirement of veteran Tory Harwood Harrison. He held the constituency until its abolition for the 1983 general election. From then until 2010 he was the MP for one of its successor constituencies, Suffolk Coastal.
He is noted for delaying a ban on beef in 1989, and for the way he attempted to feed a hamburger to his four-year-old daughter Cordelia at the height of the BSE panic in 1990, though his daughter did not eat it as it was too "hot" and she was full.
It was announced that Gummer would be awarded a peerage in the 2010 Dissolution Honours List. He was created a life peer as Baron Deben, of Winston in the County of Suffolk on 21 June 2010, and he was introduced in the House of Lords the same day, supported by his brother, Lord Chadlington, and the composer Lord Lloyd-Webber.
Although there has never been a Lord Gummer,both he and his brother chose to take geographical titles instead of their surname.