The dénouement of the whole affair came to a head in October 1955. ‘We felt mute and numbed at the centre of this maelstrom,’ Townsend wrote as Princess Margaret drove to Windsor Castle to join her mother, the Queen and the Duke of Edinburgh for lunch. All that was said or what happened has never been disclosed, but facing up to the gravity of the situation, they discussed the princess’s situation together for once. It cannot have been easy, and when the Queen Mother said her daughter ‘hadn’t even thought where they were going to live’, Prince Philip was incensed at the triviality of the statement and replied with heavy sarcasm, ‘It is still possible, even nowadays, to buy a house.’ The Queen Mother was so annoyed by him she ‘left the room angrily, slamming the door’. Later that day, Margaret rang Townsend ‘in great distress’. She did not say what had passed between her and her sister and brother-in-law, ‘but doubtless the stern truth was dawning on her,’ he observed.

Prince Philip had largely kept his silence during the discussions, but he was there to lend a private ear to the Queen when she needed his support, which of course she did. She was just too close and emotionally involved to decide between her wish for her sister’s happiness and the need for the royal family to do the right thing.

On Monday 31 October 1955, Margaret and Townsend met for the last time at Clarence House. Their love story ended with words crafted by Townsend on a rough piece of paper. This became the princess’s statement later broadcast to the world. When she read out what Townsend had written, she quietly and sadly agreed: ‘I have decided not to marry Group Captain Townsend,’ she began, when the statement was issued that evening at 7pm, and continued: ‘I have reached this decision entirely alone, and in doing so I have been strengthened by the unfailing support and devotion of Group Captain Townsend.’

Although he may not have been close to her, if proof of his loyalty to his sister-in-law was needed, four years later Prince Philip walked Princess Margaret down the aisle on her wedding day. It was the first royal wedding to be fully televised and the Duke of Edinburgh accompanied Margaret from Buckingham Palace to Westminster Abbey in the Glass Coach. Before they left he kept hurrying Margaret as, being a naval man, he hated the thought of being late, even by a couple of minutes. As a fanfare of trumpets heralded her arrival at the abbey, Prince Philip turned to her and whispered, ‘Don’t know who’s more nervous, you or me,’ adding: ‘Am I holding on to you or are you holding on to me?’