Is there a secret formula for having a Christmas Number One?

While bookies in the UK start to place bets on who’ll be #1 on Christmas Day, new research suggests there is actually a formula for having one.

English label Ostereo analysed every UK Christmas #1 in the last 50 years and found there was definitely a trend.

It seems a Pet Shop Boys track pushed all the buttons.

Howard Murphy, a founder of Ostereo, said, “I think we’re a long way from an algorithmically-generated Christmas number one.

“But certain characteristics do make a song more likely to resonate with audiences at Christmas.”

The song needs to be 3 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.

What’s more, it helps if it’s a ballad (as the majority were), a cover version (as half were) and not necessarily about Christmas.

According to Ostereo, the Pet Shop Boys’ cover of Elvis Presley’s 1972 hit “Always On My Mind” was the perfect track.

Their version was a Christmas #1 in 1988. It was faster than Elvis’ million-selling rendition to the “correct” speed, and Pet Shop Boys were the average age of 31.5 that year.

The country-pop song had been recorded by the likes of US country music singers BJ Thomas, Gwen McCrae and Brenda Lee before Presley had a shot at it as a statement of his split from his wife Priscilla.

A 2013 poll ranked it as his most loved recording.

There have been 300 different cover versions of the song.

The Pet Shop Boys did the song during a TV special where a number of major artists were asked to do Elvis covers.

Their synth-pop version went down so well they decided to record it and issue it as a single.

It reached #10 in Australia but also went on to be a #1 not only in the UK but in Germany, Canada, Finland, Poland, Sweden and Switzerland.

German disco group Boney M’s 1.87 million selling cover of “Mary’s Boy Child” (1978) came was second in the Ostereo research.

It had a tempo of 113 bpm, running 4 minutes and 2 seconds, and a key of F, two semitones lower than G.

Little wonder then it remained at #1 in the UK for eight weeks.

The song had been written in the 1950s as a song for a birthday party, and with a calypso version because most of the guests would be West Indians.

It had already been a massive seller for R&B singers Harry Belafonte and Mahalia Jackson before Boney M.

It was also a favourite with church choirs and translated into many languages.

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.”