That, in my experience, is what usually happens and it is always most impressive because by that time the seal is usually missing and the writing is both illegible and unintelligible anyway.’

He strongly advised them to look after the charter ‘because, throughout history, a document of some sort had always been looked upon as a sort of passport to respectability and, without it, you will never be able to prove – whatever it is you want to prove.’

On modernising Buckingham Palace

He also tackled the age-old custom of the bottle of whisky that appeared by the Queen’s bedside every night, even though she had not ordered it. He discovered that Queen Victoria had once had a cold and had asked for a Scotch before bedtime. As the order had never been rescinded, the servants continued to bring whisky every night some eighty years later.

On popularity

Prince Philip was never much taken in by his opulent surroundings. ‘In the first years of the Queen’s reign, the level of adulation – you wouldn’t believe it,’ he said. ‘You really wouldn’t. It could have been corroding. It would have been very easy to play to the gallery, but I took a conscious decision not to do that. Safer not to be too popular. You can’t fall too far.’