Conservative former minister Sir Tony Baldry has announced he is standing down at the general election.
The Tory MP for Banbury, who was first elected in 1983, said the introduction of fixed-term parliaments along with his age had prompted him to quit the House of Commons.
The 64-year-old, who is the latest of a number of Conservatives to announce that he will not contest his seat, insisted he was "fully confident" that the Tories would win the election.
"One of the consequences of now having five-year fixed-term Parliaments is that, if I succeed in being re-elected at the forthcoming general election, given my age, most people will assume that Parliament will be my last," he said. "I think this creates a danger that I may be unable to be as effective as I would wish to be; and that the constituency will be distracted from more important issues by the need to choose my successor.
"So, after careful thought over the summer recess and discussions with my family, I have decided to stand down at the next general election." Sir Tony, a barrister by profession, entered the political world as a personal assistant to Margaret Thatcher in 1974, earning him the nickname the "keeper of the hairspray" in Private Eye.
He was appointed to Baroness Thatcher's private office when she became Conservative leader the following year and was made a junior energy minister shortly before she was ousted.
Sir Tony went on to hold a number of other frontbench roles under Sir John Major, including his final post as agriculture minister.
Since the 1997 Tory election defeat he has served on a number of select committees and chaired the international development committee between 2001-05.