Prince William has been scoffing greasy £5 fry-ups in between his shifts as an East Anglian Air Ambulance pilot.

Prince William

Prince William

The 34-year-old royal's wife Catherine has been trying to kick his naughty eating habits by placing him on a strict regime, but it seems her health kick isn't working for him as he was spotted chomping down on sausage, bacon and eggs behind her back in Cambridge Airport's staff canteen.

A source told The Sun Online: "William seems to be a lot slimmer and trimmer these days thanks to plenty of exercise and Kate feeding him healthy meals at home. But it's a different story when he is at work. The canteen does excellent fry-ups and he can't resist them."

It seems William takes after his father Prince Charles when it comes to his love of food as the 67-year-old royal - the son of Queen Elizabeth and Prince Philip - stashes any of his leftover grub inside tupperware containers.

Chef Carolyn Robb - who cooked for Charles and his sons William and Harry from 1990 to 2000 - said recently: "The prince was very economical and very much believed that nothing should go to waste. If there were leftovers, they'd be used one way or another. If not for him, then rehashed and used for a meal the following day. But we were always quite careful: he never wanted to have huge amounts of food on the plate. They were always very thrifty and economical. If we made roasted lamb and there was leftovers, we'd probably go and make Shepard's pie the next night."

Meanwhile, Catherine's determination to help William shed the weight comes ahead of their eight-day trip to Canada.

The couple - who got married in 2011 - are taking their children George, three, and Charlotte, 16 months, across the pond with them as they carry out 30 royal engagements.