Attending the Queen that day were five doctors – her surgeon-gynaecologist Sir John Peel, who had been present at the birth of her three elder children; her new family doctor, Dr Ronald Bodley Scott; Sir John Weir, eighty-two, who had been one of her physicians since 1952; John Brudenell, a consultant at King’s College Hospital; and Dr Vernon Hall, dean of the Medical School at King’s College Hospital – and two midwives: Sister Annette Wilson and Sister Helen Rowe.

Also there was Betty Parsons, whose relaxation techniques and no-nonsense advice had helped thousands of women to deal with the concerns and fears of childbirth. Betty paid attention to breathing and, in one of her most famous exercises, would extol both the expectant mothers and the many fathers-to-be who attended her anti-natal classes to pant like a dog. Relations were not of the smoothest between Parsons and the doctors, who, most conventional in their methods as befitting their eminent positions, had little empathy with Betty’s newer, ‘alternative’ approach. The Queen, however, had enjoyed her training sessions with the former midwife and insisted that she be there at the birth. Philip, too, was supportive. He had drawn the line at attending her pre-natal classes – it was hardly the Duke of Edinburgh’s style – but when Betty had arrived at the palace the morning the Queen went into labour, it was Philip who had quickly ushered her into the delivery room before the doctors could lock her out.

By this stage, though, the doctors were too involved in looking after their patient to worry about Betty. The baby was not due for another week and only the previous morning the Queen had been out walking in the palace grounds with her corgis and Andrew, seemingly on course for a full-term pregnancy. But the contractions had started early the following day and by the evening she was in full labour.

The delivery was slower than they might have hoped for. It was at this point that Philip’s good humour proved so valuable. ‘It’s a solemn thought that only a week ago, General de Gaulle was having a bath in this room,’ he remarked when he walked into the bathroom and saw all the glum faces. It was said in a jocular way, which helped ease the tension that had been building up among the doctors and the nurses attending their sovereign.

Despite the involvement of Parsons, the Queen did not have what today would be called a ‘natural’ childbirth, though by the standards of the time it was regarded as very straightforward and the Queen did not suffer a lot of pain. The birth, however, was ‘a bit slow’, which was why Philip’s asides were appreciated. Finally, at 8.20pm, to the relief of all involved, the Queen was delivered of a ‘small but healthy’ boy.