Sir Paul McCartney had no idea the plug had been pulled on his rocking duet with Bruce Springsteen at London's Hard Rock Calling event this summer (12) because he was having such a good time onstage.

Springsteen brought out the Beatles legend as a special guest towards the end of his three-hour gig in Hyde Park and launched into Fab Four hits Twist and Shout and I Saw Her Standing There - but before they could wrap up the show, a concert official turned off the stars' microphones as the bash had overrun strict curfew rules.

The incident hit headlines around the world, but MCCartney admits both he and The Boss weren't initially aware of the sound problem as the old pals were too busy jamming together.

In a new interview with Britain's NME magazine, MCCartney explains, "We’re rocking away, all our monitors stayed on, so we weren’t really aware that the plug had been pulled on the audience, that you see on the YouTube (footage) later, it’s all gone dead."

The embarrassing cut-off prompted MCCartney to apologise profusely to Springsteen and his E Street Band for the lousy technician responsible for the abrupt ending - but they couldn't help but laugh about the whole debacle.

He says, "You’ve gotta’ have a laugh, it would just be so terrifying if you didn’t so we just had a laugh afterwards, I was just apologetic like, ‘I’m sorry, man, only in Britain!’. It’s the only place... You can’t imagine in New York somewhere like that, them pulling the plug, and it got everyone of course, so that was the big story. Everyone in America was going to me, 'Is it true, man? They pulled the plug on you and Springsteen?!' I'm saying, ‘Yeah, well, you know, just some guy: some bloody jobsworth!'"

MCCartney also revealed the decision to join Springsteen onstage was a last-minute one - and he wasn't quite prepared to revisit his old songs: "At last minute, I sort of have to say, ‘Yeah, I’ll do it', so I go on, and it’s great – they (the band) really have rehearsed it, and I’m the only one who sort of doesn’t know it, even though I wrote the bloody thing."