In contrast to his health-conscious wife, Prince William reportedly loves greasy fry-ups.
The 34-year-old royal reportedly cannot resist having a full English breakfast during his working day with the East Anglian Air Ambulance - although his health-conscious wife Kate Middleton prefers to cook less calorific meals at home.
A regular at the work canteen, where the English breakfast costs £5, said: "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."
Another eye witness revealed that despite being the future King of England, Prince William is not afforded any favours in the canteen, meaning he queues with the other employees for his favourite meal.
The source told The Sun on Sunday newspaper: "Everyone queues together and there are no special favours even if you are a prince.
"I guess he likes the fried breakfasts because it's a change from the healthy stuff he gets served by his wife."
Staff have reportedly been told not to approach or speak to Prince William unless he speaks to them first, but one employee has already broken the rules.
The source explained: "Someone broke the rule when they saw him getting a traditional full English breakfast.
"They told him, 'You shouldn't be eating too many of those. You'll get fat'.
"Quick as a flash, Wills said, 'It looks like you've had a few too many yourself'. Everyone saw the funny side."