Music experts 'find' formula for the perfect Christmas song

Researchers have crunched the numbers on Christmas songs in a bid to find the perfect formula for a festive hit.

Always On My Mind hits the ideal length and key exactly.

Experts at a UK music label have looked at every Christmas number one from the last 50 years to see what they have in common.

And their latest research has determined that the Pet Shop Boys' Always On My Mind came closest to being the quintessential tune for the holidays.

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"I think we're a long way from an algorithmically-generated Christmas number one," said Howard Murphy, founder of Ostereo which conducted the research.

"But certain characteristics do make a song more likely to resonate with audiences at Christmas," he added.

For a song to hit the top spot on Christmas Day it needs to be three minutes and 57 seconds, in the key of G major, played at 114 beats-per-minute and performed by a 27-year-old solo artist, according to the research.

Mary's Boy by Boney M came a close second, researchers said, with a tempo of 113 bpm, length of four minutes two seconds and a key of F, two semitones lower than G.

Mr Murphy said: "You can't turn an average song into a hit at any time of year - never mind Christmas - so adding sleigh bells to a Christmas song won't make a difference if the song isn't already great.

"But certain characteristics do make a song more likely to resonate with audiences at Christmas. Clever instrumentation can enhance the festive feel of the song.

"For example, without the church bells at the end, East 17's Stay Another Day is still a great song, but it's not a Christmas song."