Paloma Faith was interrupted mid-song at a recent gig when Reading FC's chairman leapt on stage to give her a hug.
The New York singer was performing at the Waitrose Summer Party at London's Natural History Museum when Sir John Madejski made his move, reported The Sun.
A guest at the party told the newspaper: "When John first staggered up on stage nobody really knew who he was. He was wearing a similar suit to the security staff so they assumed he was one of them.
"It wasn't until he approached Paloma and opened his arms as if he was trying to hug her that they sprang into action."
Onlookers at the event included Waitrose Magazine columnist Pippa Middleton, TV presenter Phillip Schofield and chef Heston Blumenthal.
Sir John, who was removed by security to the top of the museum's staircase, reportedly claimed he was just trying to shut the crowd up so that he could listen to Paloma.
Never Tear Us Apart singer Paloma had made a few comments about guests' disinterest and introduced one song by saying, "for anyone who cares enough".
She later dedicated her song Freedom to Sir John.
After the event she said: "It must have been all the free champagne. Thank God I'm from Hackney because I don't fear anything. I didn't flinch. I've seen worse and done worse."