Long-serving Conservative MP for North West Norfolk Sir Henry Bellingham is standing down.
The MP said he wanted to depart gracefully before people started saying "poor Henry, he is not quite as active or dynamic as he used to be".
In a letter to local party members, Sir Henry, who is 64, said he had "agonised" over the decision.
He described the present Parliament as "one of the most discredited and disliked in history".
Sir Henry said he thought "very few sitting MPs will be able to shake off this plague on all your camps".
He was first elected MP for North West Norfolk in 1983, losing his seat in 1997 but regaining it four years later.
The agent for North West Norfolk Ian Sherwood said he was saddened to hear that Sir Henry was standing down and thanked him for all he had done.
In 2009, Sir Henry noted in a parliamentary debate that he was a distant relative of John Bellingham, the only man to assassinate a British prime minister - Spencer Perceval.
Sir Henry studied at Cambridge University, where he received a law degree.