Prince Philip birthday: Cheeky reason Duke may 'sneak out' of Windsor when he turns 99

Mr Ship quipped: “He’s going to be one year off 100 when he has his birthday.

“I wonder whether he’ll be out celebrating.

“We’ll probably see him actually sneak out of Windsor Castle.

“Maybe pop down to see if he can find any pubs serving alcohol through the window.”

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Ms Robinson added: “He’s never one to like a fuss though.

“So whatever he does, I imagine it’ll be very low-key.”

Mr Ship replied: “It might even involve a carriage.

“There haven’t been any pictures of him carriage riding since he moved to Windsor.”

The list of workers he thanked included binmen, food production workers and those keeping the postal and delivery services going.

Ms Robinson said: “That was very rare message, we don’t hear from the Duke of Edinburgh anymore.”

Mr Ship added: “He’s got a birthday, the Queen’s got an official birthday, maybe they’ll put two together.”

The Queen’s official birthday is always on the second Saturday of June, which will be the 13th this year.

Her actual birthday is April 21.