They're famous for their command of both the majesty of rock and the pageantry of roll - but since This Is Spinal Tap came out in 1984, actual live performances from the spoof metal group have been frustratingly rare.

Now, brilliantly, Spinal Tap are due to play Wembley Stadium on July 7 as part of Al Gore's Live Earth extraganza. They've also made a new documentary, so far screened only in New York, that examines their deeply-held commitment to reducing carbon emissions. According to Rob Reiner, who directed the original film, there's also a new single on the way, entitled Warmer Than Hell.

Explaining Tap's newfound sense of responsibility, Reiner explained: "They're not that environmentally conscious, but they've heard of global warming. Nigel [Tufnel, guitar] thought it was just because he was wearing too much clothing - that if he just took his jacket off it would be cooler."

Actually that's not very funny, is it? But never mind - we can imagine a Spinal Tap performance being one of the highlights of Live Earth. The problem with Live 8 was the preponderance of hand-wringing balladry - we're looking at you, Dido - which, over the course of an entire day, sapped the crowd's spirit (well, that and the lack of alcohol onsale). The prospect of Spinal Tap bowling up and unleashing the hilarious likes of Tonight I'm Gonna Rock You and Big Bottom is an exhilarating one.

To mark this hallowed occasion, here's the memorable "exploding drummer" sequence from This Is Spinal Tap - a fabulously well-observed scene that every band, without exception, always quotes when they're asked to explain how they got together. It's even more impressive when you consider it was all improvised.