ABBA still holds the title of the biggest success story to come from Eurovision.
The group, who won the song contest in 1974, were propelled to world fame overnight.
Made up of two sets of couples, the foursome sold 385 million records worldwide - only being outsold by The Beatles.
The band was named after the initials of the band members Agnetha Fältskog, Björn Ulvaeus, Benny Andersson, and Anni-Frid Lyngstad.
Their music inspired the theatre and film adaptations of Mamma Mia! which has been watched by over 54 million people across the world.
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With Eurovision back in full swing, Björn has shared his two rules that if followed, could result in winning the competition.
His first tip was to take a risk with the song choice.
The group blew audiences away with Waterloo, which they chose to sing in English, rather than their native tongue.
But it was only narrowly chosen as their entry, rathan than "Hasta Manana".
Speaking to The Independent, he said: "It might sound ludicrous today, but then it was quite a hard decision to make.”
He said that the song was a solo for Agnetha and felt more appropriate for Eurovision.
"Waterloo was riskier. We took a chance, knowing it was going to be different from all the others. It could have been ‘Hasta Mañana’ and this would never have happened. It would never have won,” he said.
Björn also said how the group made an impression with their bold and colourful outfits.
Talking about his difficulties getting into his clothes ahead of the competition, he said: "I was overweight and couldn't sit down because my trousers would split".
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But when they arrived at the finals in Brighton, their outfits caused them more grief.
He said how there was a "mistake" when they won as the writers were called up on to the stage first.
When Björn tried to join Stig and Benny he was stopped by a security guard who didn't believe that he was involved in the writing, telling Björn that "writers don't look like that".
But Carl Magnus Palm, the author of ABBA's biography Bright Lights, Dark Shadows said that the band were "intent on making an impression" and "weren't leaving anything to chance".
“You dress up in crazy costumes, you have Napoleon as conductor, everything you could ever think of to make a splash, to make them noticed,” he said.
Agnetha Fältskog was married to Björn Ulvaeus and Benny Andersson who was married to Anni-Frid Lyngstad.
Both sets of couples split just a few years after winning Eurovision.
Agnetha married Björn on July 6, 1971.
They had two children together — Linda Elin Ulvaeus, born February 23, 1973, and Peter Christian Ulvaeus, born December 4, 1977.
The couple announced their separation in January 1979, with their divorce being finalised in July 1980.
The other two band members, Benny and Anni-Frid, were married in 1978 after a lengthy nine-year engagement.
Their marriage didn't last and they divorced in 1980.
They don't share any children together.
This year's Eurovision is being held in Sweden, which prompted many to speculate over whether ABBA would perform.
But the group have refused to reunite for a performance on the night, so organisers are now trying to bring their digital “ABBAtars”, from London’s ABBA Voyage show to the stage instead.
But technical issues may prevent that, which is why a medley by a series of pop stars is being lined up as a potential alternative.
