Jason's back with a bang in comedy.
The Only Fools And Horses star takes the lead role in new six-part series The Royal Bodyguard, playing the hapless Captain Guy Hubble who, after a blunder of his own making, is promoted to be the Queen's private bodyguard.
"He's a coastline short of a boulder," says Sir David with a roar of laughter.
"His job's happened because of an accident but his heart is in the right place, he's got a great sense of duty and is a very oldfashioned, military man."
Sir David Jason as Guy Hubble But Hubble is useless at organising and finds that chaos follows his every step.
Sir David, 71, explains: "I get thrown into mud, pulled into tanks of water. I had to swing on pipes, jump down a chimney, I get covered in soot, mud, water, and even wrapped in cellophane.
"But I thoroughly enjoyed making it, despite some of the stuff they made me go through. Have you got that down?" he orders, laughing. "M.A.D.E. Made me do!" Anyone who has seen the famous moment in which Del Boy falls through the bar in Only Fools And Horses will know that the actor is comfortable with slapstick, and The Royal Bodyguard - hailed as his big return to comedy - has it in droves.
The humour is of the family-friendly kind which Sir David reckons is missing from TV today.
The Royal Bodyguard BBC1, Boxing Day, 9.30pm