Britain's longest serving MP to step down, but will it give Boris Johnson a possible route back into Westminster?

Britain's longest-serving MP Sir Peter Tapsell speaking in the House of Commons, as he has announced he is to stand down at the next general election. The Conservative will tell his local association tonight that he will not fight the 2015 campaign. Sir P (PA)

Britain's longest-serving MP is to stand down at the general election, potentially clearing the way for Boris Johnson to return to Westminster.

Sir Peter Tapsell, 84, is to retire next year – 56 years after he was first elected as a Conservative MP at the age of 29.

His decision to stand down in the safe seat of Louth and Horncastle in Lincolnshire, which he held at the last election with a 13,871 majority will intensify speculation over the Mayor of London’s intentions.

David Cameron said he wants the Mayor of London back in the Commons after the election.

Mr Johnson has always insisted that he will see out his term in the capital, due to end in 2016, but the Prime Minister suggested he “can stay on as mayor and come back to the House”.

As a result of his lengthy parliamentary service, Sir Peter is Father of the House, the title bestowed on the MP who has served in the Commons for the longest unbroken spell.

Sir Peter won West Nottingham from Labour in 1959, only to lose it five years later. He returned to the Commons two years later.