Led Zeppelin were ''really tense'' when they reunited for a one-off gig in 2007.The surviving members of the group, Jimmy Page, John Paul Jones and Robert Plant, performed at London's The O2 - for which they were joined by late bandmate John Bonham's son Jason - in tribute to late music executive Ahmet Ertegun, and though they weren't nervous about playing together after so many years, they found the experience ''intense. Speaking at the UK premiere of 'Celebration Day' - the DVD concert film documenting the gig - at London's Hammersmith Apollo, Jimmy told BANG Showbiz:''My memories of the evening was that it was really intense. We had really worked towards it, and we knew we had this one shot, this window when we were going to in and let people know what our reputation was about in the first place. ''I wouldn't call it nervous, but the adrenalin tap went on really early and I was getting really sort of fidgety, and ready to get on. And that's it, I went in there and I just remember it being really tense. And then it was over all too quickly.'' Although the band hadn't planned to release the footage of the gig, they are pleased they did because the finished film is so great. Robert said: ''When we did this gig we didn't know what we had done, so we kind of crept up on the movie as time went by, and realised we are getting that much older and stuff, and it sounds great and looks like we're having a good time.''