When the Prince of Wales and the Duchess of Cornwall visited a jazz workshop in July 2014, which was part of the Edinburgh Jazz & Blues Festival, they were following in a long tradition of British royalty demonstrating their enthusiasm for jazz.
Buckingham Palace itself was named as a "significant British jazz location" in 2009 and given a (Kind of) Blue plaque – it was the 50th anniversary of Miles Davis's Kind of Blue album – in recognition of being the venue that hosted the first jazz performance before a head of state. That was in 1919, when the Original Dixieland Jazz Band played a command performance for King George V.
George V (Prince Charles's great-grandfather) cried out his approval during the tune Tiger Rag, and he must have enjoyed the experience because jazz musicians, including Sidney Bechet and Louis Armstrong, were invited back to the palace several times during his reign. The king was particularly taken with Bechet's composition Characteristic Blues. Bechet, incidentally, also gave music lessons to Charles Henry Maxwell Knight, a future British spy who was apparently the inspiration for the character M in Ian Fleming's James Bond novels.
The king was also wowed by trumpeter Armstrong, who dedicated one song to him with the words: "This one's for you, Rex."

 
In an interview in 1955, Armstrong recalled: "The biggest laugh about me and the king was when I was playing the tune (I'll Be Glad When You're Dead) You Rascal You for him in 1932 and I hollered: 'This one's for you, Rex – that's what I called him 'Rex'.
Asked; "Was the King a 'cat'?", Armstrong replied: "He's got to be or I wouldn't call him Rex. You see when you're a cat you appreciate your nickname."
Armstrong didn't add that it was a New Orleans tradition, perhaps jokey, to call the white king of the Mardi Gras, 'Rex'.
Hiring black entertainers was nothing new for our royal family. Minstrel Billy Kersands (dancing with a mouthful of billiard balls), and tap dancer Juba, had performed for Queen Victoria and Bert Williams taught Edward VII how to do the "cakewalk dance" on the lawns of Buckingham Palace. But it was George V's son, the Prince of Wales (later King Edward VIII and the Duke of Windsor) who was perhaps the most ardent jazz royal. This was a time when black musicians, most of them playing jazz, were all the rage among London’s rich and beautiful rich set.
His affection for jazz had started when he became an ardent fan of American cabaret singer Florence Mills – she sang risqué songs such as I’m Cravin’ For That Kind of Love – when she toured the UK with her revue, Blackbirds in the mid-Twenties. The Prince of Wales often went to see jazz concerts with his younger brother The Prince George (Duke of Kent), who had an affair with the singer.
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The Prince of Wales seems to have been more interested in the music and he fancied himself as a drummer, too. He ended up playing drums (rather poorly, one imagines) during a concert by Grenada-born singer and pianist Leslie Hutchinson at a party thrown by Lord Beaverbrook. He also became friends with Duke Ellington in the early Thirties, and it was a friendship that lasted the rest of his life. After the Prince (then King Edward VIII) abdicated to marry American Wallis Simpson, he moved to New York and would often invite the Ellington Orchestra to perform at charity events for which he was a patron.

 
Ellington also maintained contact with the royals back in the UK. When Ellington and his orchestra played a concert at the Leeds Festival in England in 1958, Queen Elizabeth was taken with the music and Ellington was invited to Buckingham Palace to meet her. He told the Queen that "something musical will come from this", and so it did. He subsequently composed a suite of six songs which he dedicated to the Queen. One of them, a solo piece for the piano called A Single Petal of a Rose, was written about their meeting. Back in America, in April 1959, he recorded the set at his own expense and had only one pressing made, which he sent as a gift to the Queen.
The Queen Mother also enjoyed jazz and would make a point of attending dances at the University of London (where she was Chancellor) when there was a band playing jazz. She even did so in November 1969, whe the Swing Kings were playing, as a detour on her way to 21st birthday celebrations for Prince Charles.

 
Elizabeth's sister Margaret was also a jazz fan. She would sometimes go to Ronnie Scott's club in London, and would frequently drop in to see late sets by George Melly and John Chilton's Feetwarmers. At a Melly concert in the early Eighties, incidentally, Princess Diana danced with David Bowie to a Fats Waller song.
Margaret also maintaned the tradition of British royals seeing Armstrong perform, including at London's Empress Hall in 1956. Armstrong, in turn, maintained his habit of being jocular about the royal family, telling the British press: "Your Princess Margaret is one hip chick."
Fast-forward four decades and Margaret's nephew, Charles, was in Scotland to hear how band's such as Artscape's Youth Band, a South African group comprising youngsters from the townships of Cape Town, are keeping jazz alive in the grand tradition of a Duke (Ellington) a Count (Basie) and a King (Oliver).
Charles and Camilla joined Jools Holland for a concert by renowned pianist Stephanie Trick at the Edinburgh Jazz & Blues Festival. Holland said: "It's great that the royal couple have come here to shine a light today, because it will draw attention from all over the place to the fact that the jazz festival is on and it's one of the best jazz festivals in the world. Their interest and them coming today will expand that everywhere."
It's fitting that one of the tunes being played at a special gala concert to mark the Queen's 90th birthday will be Alexander’s Ragtime Band, a song heard at Buckingham Palace more than a century ago.