He enjoyed ballroom and Scottish dancing and was taught, as his mother had been, by Miss Vacani, who came to the palace to give him lessons with other children belonging to members of the household. But he found it difficult to mix and would cling to Nanny Lightbody and would watch as Anne ‘would go off with the other children’. And while Charles was often too shy to talk, ‘Anne talked non-stop’. When he was nervous, Mrs Parker noted, his mouth would twitch to one side in the manner later seized on by comic impersonators.

It had quickly become apparent that Princess Anne was growing up very differently. She once observed that she should have been a boy or, as she says, she would have ‘probably been regarded as a tomboy’. There are those who are close to the royal family who believe that not only should she have been born a boy, but that she should also have been the eldest. Philip was one who held that view.

Single-minded, sporty and brave, Anne is unimpressed by rank or title, is unafraid of controversy and cares little for the opinion of others. And if she can be disconcertingly ‘royal’ when the mood takes her (‘I’m not your “love”, I’m your Royal Highness,’ she once admonished an over-familiar photographer), she is someone who has no qualms or reservations about letting her hair down and mucking in when the occasion so demands. In other words, she is very much her father’s daughter – in a way that Charles could never be his father’s son.

‘He always had more fun with Anne,’ Eileen Parker observed. ‘Charles is more like the Queen, while Anne is very like Prince Philip.’ As Philip himself would later admit: ‘Perhaps I did spoil her at times.’

‘Anne would boss Charles; she would take command of things,’ recalled Mrs Parker. ‘If she saw a toy she wanted, she would grab it. She also grabbed everything that Charles wanted – and everything he had she wanted.’

Charles had a blue pedal car he was particularly fond of. He was often unceremoniously bundled out of it by his more aggressive sister. It was the same with the tricycle they shared. If Charles was riding it, Anne was sure to want it. ‘There were terrible scenes,’ said Mrs Parker, who used to entertain the royal siblings at her home in Kensington’s Launceston Place. ‘Nanny Lightbody would say, “Now stop this!” ’

There was no stopping Anne, however. When their father presented them each with a pair of boxing gloves and tried to instruct them in the art of self-defence, they set about each other with such fury that he had to take them away again.