Prince Charles is the slowest of royal eaters, while the Duke of Edinburgh is the fastest and gobbles his food up so quickly he has been known to put more fastidious eaters right off their food. One footman recalls a dreadful night when they were sailing onboard HMY Britannia when it was struck by a force nine gale. Everyone retired to their cabins, including most of the ship’s company. Not so Prince Philip. He still wanted to eat dinner, and his poor equerry had to sit with him. He was getting greener and greener as he watched Prince Philip, never the neatest of eaters, shovel food into his mouth. Eventually, when he was asked if he would like some rice pudding, he could take it no longer and had to leave abruptly. Prince Philip was left all on his own in a dining room that can seat sixty, unworried about the discomfort he had caused.

A more common problem than Prince Philip’s eating habits is guests simply being lost for words in the royal presence. ‘There’s a lot of trembling knees – and people can’t talk sometimes,’ says Prince William. ‘It’s quite difficult talking to people when they can’t talk. You don’t get very far. I don’t get past the hellos!’

When the head of state from a foreign power is the guest of the Queen and the Duke of Edinburgh, they stay at Buckingham Palace or Windsor Castle. On the day of arrival, which is always a Tuesday, they are given lunch in the Bow Room at the palace or the State Dining Room at Windsor Castle. These state visit luncheons are rather grander than the small and cosy ‘meet the people’ occasions that the Queen and the Duke host a few times a year. Everything, as the Queen explains, is truly formal.

‘A lot of the visits nowadays have a very strong political theme to them,’ the Queen says. ‘We are the hosts. Basically, we give the entertainment initially and have people to stay hoping to give them a nice time to remember. Obviously, we keep up as many of the traditions as we can, like going in carriages.

‘I think that in a way that it’s quite an old-fashioned idea that you do put out the red carpet for a guest. I think people don’t really realise this. I do tell guests that we put on our best clothes and everybody dresses up and the best china and the glass and the gold plate come out, otherwise it doesn’t see the light of day! It’s very nice to be able to use it and show it. If you do put out the best china and glass it isn’t necessary to make it overwhelming.