Queen Elizabeth II had a passion for music she rarely talked about in public. She was a devoted fan of Duke Ellington's music, especially Take the A Train – a song she danced to regularly as a newlywed holidaying in Malta – and was fulsome in praise of the great pianist and bandleader when she met him in 1958 and again in 1973.
She had some other surprising favourites, too. The Canadian folk singer Gordon Lightfoot once told me that when he met the late Queen in Ottawa at a Canada Day celebration in the early 1970s, she told him how much she loved the Canadian Railroad Trilogy. "She looked at me and said, 'oh, that song', and then said again, "that song", and that was all she said," he recalled.
Perhaps the most intriguing thing musically, however, is the Queen's own brief time as a singer, when she recorded with pianist, composer and bandleader Laurie Holloway in duets with her sister Princess Margaret.
Holloway, who is now 84, has played with some of the most famous women of the modern era, including Judy Garland and Ella Fitzgerald. But one of his most memorable recording sessions was at Buckingham Palace when he was accompanying the royal sisters.
Holloway was asked to help Elizabeth and Margaret record songs as a present for the late Queen Mother's 90th birthday in August 1990. At the time, Oldham-born Holloway was the musical director of the Michael Parkinson show and was also known for composing the theme tunes for the television shows Blind Date and Game for a Laugh. He later became the first musical director of the hit BBC show Strictly Come Dancing.
"Princess Margaret was a good friend of mine and my late wife, the American singer Marion Montgomery," Holloway tells me. "Princess Margaret used to come to my home in Berkshire on occasions for a knees-up, some food and a sing-song. She knew the lyrics to every song. I asked her once, 'how do you know all those words to everything,' and she said, 'Oh, Mr Coward taught me'."
As well as being a friend of playwright and songwriter Noel Coward, Princess Margaret would regularly attend concerts at Ronnie Scott's jazz club in Soho. Margaret, like her sister, was a big fan of Ellington.
"Princess Margaret and I became quite friendly and one night the phone rang and she asked if I was free the following day," adds Holloway. "She asked if I would come to Buckingham Palace and play the piano with her and Queen Elizabeth II, who wanted to record a tape for their mother's birthday."
Holloway said he asked Princess Margaret to "give me a clue" what they were planning to sing and she mentioned a 1919 musical hall song called Where Do Flies Go in the Winter Time?, which they remembered enjoying singing as children.
"I called Chappell's Music Sheet store in Bond St and asked them to bike me over the sheet music," recalls Holloway.
"I turned up at Buckingham Palace with this music and Princess Margaret said, 'it's the wrong one!' She wanted the tune written by Sam Mayo and Frank Leo. The other songs I didn't know and had to learn quickly, otherwise it might have been 'off with his head'," joked the musician, who also worked with star singers Mel Torme, Liza Minnelli and Shirley Bassey during his career.
Holloway said the royals loved the lyrics of Where Do Flies Go in the Winter Time?:
When they've finished buzzing round our beef and ham When they've finished jazzing round our raspberry jam Do they clear like swallows every year? To a distant foreign clime Tell me, tell me, where do flies go in the winter time?
He asked Princess Margaret about the choice of songs. She told him they wanted to record nursery rhymes that had been taught to them by their grandfather, Claude George Bowes-Lyon, 14th Earl of Strathmore and Kinghorne, who had sung with them when they visited Glamis Castle in Scotland.
"We did about 14 tracks in all that day with the Queen and Princess Margaret and a couple of ladies in waiting. The session was recorded by a soundman from the BBC, who used a microphone for each of the singers.
"I just took over and said, 'right, you sing without accompaniment and then I will know which key you are in, then I'll know the routine and off we go'. So we did 'rehearse-record', as you do in the studio as a musician, and then we all listened to the results.
"Princess Margaret sat on the big chair and the Queen sat on the little chair while we played the cassette tape of the songs."
So what was the Queen like as a singer? "Both royals were all right as singers, they were like amateur dramatic performers rather than a Kiri Te Kanawa or Marion Montgomery, but they were certainly more than adequate. I didn't get nervous. That's what I did for my job," says Holloway.
After the Queen Mother's 90th birthday in August 1990 – which was celebrated with a concert at the London Palladium featuring Placido Domingo and Kiri Te Kanawa – she was presented with the tape by her daughters.
"Princess Margaret came to my house some time later and said the music was a great success. She told me they had taken it to their mother's house and the Queen Mum said 'we'll have to go and sit in the car to hear it', so that's what they did.
"Margaret told me that Prince Charles then said that he wanted to hear the tape of the Queen singing and was told 'you will have to go and listen in the car'. He said, 'why?'. Then he opened a cupboard inside her house and there was loads of hi-fi equipment in there that the Queen Mother didn't know about."
Holloway, who received an MBE from the Queen at Windsor Castle in 2013 for his work with the Montgomery Holloway Music Trust, said the sad part of the story is that the cassette tape went missing after the death of the Queen Mother in March 2002.
"Since then I have spoken to the Queen, but she didn't have a clue as to where the tape was. It has disappeared," said Holloway. "The BBC man was told to only make one tape, in case it went public. Hopefully, he did record another one that still exists somewhere.
"Perhaps the original is stored somewhere and will be found one day. The original cassette tape box may not have had any writing on it. The whole thing came about, the Queen told me, because they simply wanted to give their mother a tape of the songs they had sung as children. That was such a nice thought."