The amazing thing about that band, and what I love about them, is that especially those two--Jimmy and Robert--are always, always, always pushing the boundaries. And one thing that happens when you push the boundaries is that you go over them--that's how you find them.

So I would find that with Jimmy, if I would just remove simple little things like an audible clunk where his finger had fallen off a string, and if I just took that stuff out, you ended up with this genius, this pure brilliance.

He pushes so much until he makes a mistake, and the mistake kind of spoils everything that had gone before. So I sort of took it upon myself to give him a helping hand there, and I did.

At the end of the day, it's an entertainment package, as well as a record of history.

But it's not a documentary: if you watch "Stairway to Heaven" from Earl's Court, halfway through the solo, Jimmy's high E-string broke. You'll see that right at the end of the solo, when that famous fanfare goes into the last verse, he plays the last fanfare an octave down. But when you listen to it, it's the octave up.

I had gone in and pinched the fanfare from another night and put it in on that night, because even though you see the visual that he's playing it down the octave, it still seems more important that you have it sonically right. But you know, there are purists and "anoraks" who would hate that. But I firmly believe that that's in the best interest of representing the band as they were, because that mistake didn't happen every night, and that fanfare was always part of "Stairway to Heaven", and why have one version in this huge anthology that had to be spoiled because of something silly like that.

Ed: Jimmy wasn't using much distortion by the time of Knebworth. Did you have to run his guitar through any extra reverb or delay during that segment?

Kevin: In places. In "Achilles' Last Stand", there's that wonderful ascending line. That's always been a harmony line in the studio recording, so I definitely took it upon myself to put the delay on there to add the harmony.

Ed: One track I would have loved to have seen was "Ten Years Gone".

Kevin: There was an awesome performance of "Ten Years Gone" at Knebworth, except that the guitar wasn't recorded. That's the truth: there's no guitar on tape. He must have used a different amp for that song, and there wasn't a microphone on it.