The 68-year-old actor – who has been playing Detective Inspector Jack Frost for the past 16 years – confirmed he will leave the long-running drama in a special two-part finale on ITV1 this summer.
“I’m the oldest detective on British television,” he said. “I just think the time has come. You wouldn’t want me to play Frost in a wheelchair, would you?
“Frost is getting a little long in the tooth. I still enjoy doing it and it’s a great part but I just think he’s got to retire.”
But it has not been decided if the character of Frost will be killed off or retired.
Sir David teased: “Perhaps he just retires gracefully, gets the gold watch and walks away – tears all round. Maybe he just hangs up his hat.”
Sir David, who is also known for playing Derek ‘Del Boy’ Trotter in the BBC comedy Only Fools And Horses, added he already has his next project in the pipeline – a black comedy/drama for ITV entitled ‘Albert Memorial’.
He said: “It’s three old farts on a road trip really, and I liked it because it is quite original and fresh and has a strong strain of humour in it.”