The royal couple, who celebrated their 19th wedding anniversary in April, have spent the day together, attending the grand State Opening of Parliament. But they will be looking forward to celebrating together privately once their duties for the day have come to an end.

According to one royal expert, Charles will likely throw a party for his wife, either at Clarence House or at Birkhall in Scotland, and will present her with a very special gift. “He likes to give her jewellery,” former royal staffer Paul Burrell revealed to Slingo.

“I think he’ll give her something special. He may have had something commissioned for a birthday. He’s very spoiling, the King, and he will make sure that all attention is on Camilla. He likes to remind her that she’s Queen. He likes to remind her that this is given by him for her service over the years to him, and this is his reward to her.”

Paul continued: “I don’t think there’ll be any public celebrations because it’s not a milestone birthday. Everything will be behind closed doors. Maybe they’ll go back to

the Ritzagain because that was a milestone when they first stepped out together. They like dining out, but why dine out when you have a fantastic chef at home?”

Of course, it’s not easy for the royals to dine out. According to Paul – Princess Diana’s former butler – Charles and Camilla’s favourite restaurants are the Ritz and Claridges because they are able to provide the necessary security and privacy.

That being said, Queen Camilla has surprisingly simple tastes when it comes to food. In an interview for You Magazine, lead by her own son, Tom Parker-Bowles, she revealed: “One of my favourite foods is baked beans on toast. Always Heinz.”

She also shared her love of “freshly cooked fish and chips, wrapped in paper” and declared that she’s not a fan of complicated cooking, preferring recipes that aren’t “too mucked about, or fussy or fiddly”. “I could fill a book with all my cooking disasters. I’m not a natural baker, to say the least. As for baked potatoes… many a poor, incinerated specimen has been found in the bottom of the Aga, put in, then forgotten about.”

When they are at home together, Camilla and Charles do enjoy eating plenty of fresh fruit and vegetables. “I love the vegetable garden. I’m very proud of my white peaches,” she added. “My husband is an excellent gardener, and we’re quite competitive about our fruit and vegetables.”