PRIMAL Scream are an odd lot. No one's quite sure when they started; no one's really sure when the various members joined, or even who's in the band.

It doesn't really matter. What does matter is that, although it's more than 20 years since Bobby Gillespie and Andrew Innes first bashed dustbin lids together to make a noise (fact), they are still making music that consistently challenges, managing to both excite and confound, confuse and surprise.

They are the embodiment of what lifestyle gurus have dubbed 'middle-escence' (late 30/40-somethings who refuse to conform) and yet as younger, trendier bands seem content to reinvent the past, Primal Scream fire salvoes of music that could have been made anywhere between Memphis and Mars.

"We've always been a bit of a thorn in the side of it all," says keyboards guru Martin Duffy who's recorded with the Primals since 1987, but has been a full time member since the 1990 release of their landmark Screamadelica album. (It was on Duffy's piano figure that DJ Andrew Weatherall built the hit version of Loaded.)

"It was music that brought us together and it's what keeps us going. I've no idea what the tour's going to be like as we haven't played since we recorded the Jools Holland New Year thing a few weeks ago.

"We've had a couple of weeks off but we're all raring to go now. We'll do three or four days of rehearsals then we're off."

Primal Scream on tour is a legendary beast. The band's propensity for hedonism knows no bounds. Their discovery of ecstasy fired the making of Screamadelica, which still stands as one of the most important albums of recent times - and before you start tut-tutting just imagine what Sgt Pepper would have been without LSD.

"Being on tour is full-on, you know. We can't just come off stage and go to our hotel rooms and be quiet, that's just not us.

"What has changed, though, is that we recognise we can't go on like that so we only tour for a couple of weeks at a time. That way you can handle the madness and then make sure you have a proper recovery.

"You have to act your age, you know, but what age do you act? We all still feel like we did when we were 16 or 17, but now it takes us longer to recover... that's how we know we're getting older."

Last autumn, the Primals played a few dates with The Rolling Stones. The comparisons are obvious - and Duffy is fulsome in his praise for the Stones - but there's an important difference: while the Stones continue to make new music, who's actually interested in hearing it?

Primal Scream released their first ever compilation, Dirty Hits, late last year, but a new Primals album is a genuine event.

"You say that but I thought the last one we did (Evil Heat in 2002) was a bit overlooked, though I suppose that's fair enough as there are more young bands who deserve the attention,"says Duffy.

"We're promoting Dirty Hits on this tour so it won't be any unfamiliar skiffle versions of stuff... though I don't know!

"By the way, Craig David's name's gonna be put on the guest list for the Southampton gig, just because I love his stuff after seeing Bo' Selecta!

"I've no idea what the new stuff will sound like, no idea. We experiment with electronics, computer technology and stuff, but then we can play real well as a band so it could be anything. When you're lucky enough to work with something as holy and sacred as music you have to let it go where it goes.

"Inspiration is spontaneous, it comes out of thin air and we've never tied ourselves to any scene or movement so we can be free to let the music go where it wants to."

Primal Scream play Southampton Guildhall on 21 January. Box office: 023 8063 2601.