But what does it take to stand the heat in the Queen's kitchen? Darren McGrady, who worked for the Royal family for 15 years - for Her Majesty until 1993, and for Diana, Princess of Wales, before her death in 1997 - says it is all about remembering the little things, from how the Queen's casserole should be seasoned to Prince William's favourite type of cake.
"I'm amazed they're advertising at all," admits McGrady, 50, who was a chef at London's Savoy Hotel before starting work as a carrot-peeler for the royal horses in 1982.
"They normally promote from within, because you have to learn the family recipes. Although you're cooking for 300 staff and kings and presidents, you're also cooking for a family; for two pensioners, with particular likes and dislikes. You'd never put garlic in the Queen's menu, for example, or strong onions or paprika, because she hates them."
The successful applicant must have a broad repertoire. As well as being an expert in souffles and sauces, they must be well-versed in the simple, frugal dishes preferred by the Queen and the Duke of Edinburgh.
For breakfast, McGrady recalls, Her Majesty enjoys Cornflakes or Special K, with fruit from her greenhouses or macadamias. For lunch, she likes white fish or grilled chicken with vegetables ("no potatoes if she is eating alone"). Dinner, at 8pm, is normally venison or salmon and salad.
A good grip of Gallic is required to write the daily menus in French. McGrady explains: "Every dish goes into the Queen's menu book, with two options for every course. She puts a line through the one she doesn't want."
New recipes must be approved by Her Majesty. "Once I included a strawberry dessert called 'Veiled Farmer's Daughter', which I'd read about in the Daily Telegraph," he remembers. "I got a note back from her asking: 'Who or what are the veiled farmer's daughters?' I sent her the recipe and she passed it."
Her Majesty takes afternoon tea every day, consisting of scones ("sometimes crumbled up and fed straight to the corgis"), sandwiches and two sweet options - chocolate biscuit cake, ginger loaf or honey sponge. Game, often freshly shot on the Sandringham estate, is always popular. And she has roast lunch - the best joint of lamb or beef, biked over from Harrods - every Sunday, but will eat only one particular cut of meat. "The Queen has to have the end piece, which is always put at the front of the tray to keep her happy," says McGrady.
Successful applicants must also cater for the tastes of other royals. If Prince Andrew is coming for tea, mangoes should be on the menu.
"Every Christmas, he'd get sent a gift of mangoes, and he'd come into the kitchen bellowing: 'Where are my mangoes?' He used to count them every day - he loved them." As for Princes William and Harry, McGrady remembers "two boys who loved burgers and pizza".
So, does he have any advice for prospective royal chefs? "Learn quickly who likes what and how they like it," he says. "Know how to address the family. Try not to stand out - no piercings or pink hair. And watch a lot of Downton Abbey. Working in the kitchens at the Palace is exactly like that."
