At the end of the tour, the Queen flew out to Lisbon to join Philip for a state visit to Portugal. During the long voyage, Philip had grown a full naval beard, which he shaved off before boarding the Queen’s plane. He found the entire party on the plane, including the Queen, wearing false ginger whiskers. When the royal couple emerged to meet 150 reporters on the tarmac, they were smiling happily. Time magazine reported that this was ‘an all’s well signal that spread to the four corners of the earth’.

Whether the unnamed showgirl referred to in the Baltimore Sun was Pat Kirkwood, a beautiful musical comedy star, is unknown. However, there were persistent rumours in the press that Philip was having an affair with her as early as 1948, when the Queen was pregnant with Prince Charles. Kirkwood, then the highest paid star on the London stage, was the girlfriend of society photographer and Philip’s fellow Thursday Club member Baron.

One evening after a performance of the musical Starlight Roof at the London Hippodrome, Baron took Philip and an equerry to meet Pat in her dressing room. The foursome then went out to dinner at Les Ambassadeurs Club in Hamilton Place run by John Mills, a Polish ex-wrestler. After dinner, they went at Philip’s request to the Milroy Club for some music and dancing. According to Kirkwood, Philip would not let her sit down and danced to whatever the band played. Later they went to Baron’s flat for scrambled eggs. Philip’s conduct had not gone unnoticed at the Milroy and rumours of an affair with Pat spread.

According to Kirkwood, they only met again when she was presented to Philip at command performances in the theatre. She later said: ‘I wish Philip had never come uninvited into my dressing room that night. I have had to live with the consequences for the rest of my life.’ The rumours persisted for years.

After her death in 2007, Pat’s fourth and last husband said: ‘I have in my possession correspondence which passed between my wife and His Royal Highness the Duke of Edinburgh which leaves no room for doubt that the allegations so often made regarding a relationship between them are entirely without foundation. It was my wife’s express wish that these letters should be handed in the fullness of time to the Duke’s official biographer in order that the truth may be finally established. Until that time, they will not be released for publication.’ Even this comment, however, does not explain why she and Philip should have been corresponding with each other at all.