It has been hailed as the sound of the summer - but doubts are beginning to surface about the chart potential of Cherie Blair's supposed Ibiza "hit".
Mrs Blair performed her karaoke session last month
Reports that a remixed dancefloor version of her singing The Beatles' When I'm 64 is storming the clubs have proved difficult to verify.
Ministry of Sound, which hosts one of Ibiza's biggest club nights, said it had not come across the tune.
"No one has heard the record," said a spokeswoman. "We were talking to our dance guys and no one's heard the record. It may be a rumour."
BBC Radio 1, which has DJs, producers and back-up staff in Ibiza, also said it was unaware of the track's existence.
Calls to DJ agencies and other club promoters were unable to shed any further light on the mystery.
Mrs Blair's rendition of the 1967 Paul McCartney song was made during an
impromptu sing-song to Chinese students in Beijing last month.
If the tune does exist, one theory is that it could be available as an unofficial bootleg in the form of a DJ "dubplate".
As the songwriter, Sir Paul would have a claim to royalties from any public airing of his tune.
His spokesman, contacted by BBC News Online, said he was on holiday and did not want to talk about it - although he, too, had not heard of the record.
"Paul's on holiday as well," he said.
Downing Street was similarly unable to solve the riddle.
"We never comment about Cherie Blair," said a spokesman.