Not all of the known world's A-list celebrities were at Glastonbury this weekend, as 200 or so fans at the 100 Club in London discovered, when Johnny Depp joined Alice Cooper on stage to play rhythm guitar on versions of the Cooper classics I'm Eighteen and School's Out.

Twelve songs into a 75-minute set, Cooper announced the arrival of a special guest, "the bluesmaster, Mr Johnny D from Kentucky". Depp's was the fourth guitar in a lineup that already had three, so in truth he did not make a huge difference to the sound, but there were no audible disgraces in his contribution.

Before Depp left the stage, Cooper reminisced to him about meeting Keith Richards of the Rolling Stones. "He said to me: 'How long is it since you stopped drinking?' I told him 20 or 30 years. He said: 'Which begs the question: why?' As he walked away, I thought: That's Captain Jack Sparrow!"

Cooper told Depp that "if this whole movie thing doesn't pan out" he could have a place in his band.

Depp has history with rock bands. He played slide guitar on the Oasis song Fade In-Out in 1997, and on Shane MacGowan's first solo album. He formed the group P with members of Butthole Surfers, Sex Pistols and Red Hot Chili Peppers, and until 2004 was part-owner of the LA rock club the Viper Room.