MUSIC legend Frankie Valli appeared live on This Morning today and went down a storm with fans as he revealed the truth behind the iconic Grease theme tune.
The song, with its instantly recognisable intro, was released in May 1978 and was a big hit worldwide, hitting No1 on the US Billboard and selling half a million copies in the UK.
But today Frankie, 82, speculated that its writer - the Bee Gees' Barry Gibb - may never have let him sing it if he knew how big it would be.
On This Morning, he said: "I can start out by telling you I was a big fan of the Bee Gees for a very long time, and Barry Gibb and I had talked many times about doing something together.
"While the movie was being shot, the Bee Gees were also doing a movie and the movie they were doing was Sgt Pepper's Lonely Hearts Club Band, and I had a call from Barry and he said, 'I wrote this song, it's perfect for you'. He sent it over and I listened to it and I loved it."