Michael Douglas and Catherine Zeta-Jones started going out together in the late Nineties many doubted it would last, primarily because of the 25-year age gap between them. 

But having now been married for 15 years, Michael insists the secret to their longevity is not taking things too seriously.

“If I forget a name or a date, she will look me in the eye and I’ll say, ‘Yes dear, I know’.

“We joke all the time about when I reach my 80s and she’s wheeling me around and I’m saying ‘Whoa, where are we going?’ And she will say ‘Cartier darling, Cartier. It’s your favourite store’.

“Remember, to keep a sense of humour about these things,” the 72-yer-old tells Jonathan Ross, pictured together, during a talk at London’s Theatre Royal Drury Lane.

Although Michael still counts his lucky stars that he’s ended up with Catherine, 47, he reckons both being actors helps: “She has a wonderful warm Welsh heart, has a great work ethic and is in the same occupation as me.