‘It was the same with Nirvana. We exploded in England before we did in America. I think the UK's always had a pretty good idea of what's about to break. If it blows-up in England, then it's only a matter of time before it blows-up everywhere else. Even so, I never imagined something like Hyde Park would work.’

There’s nothing false about Grohl’s modesty. The childish look of horror and glee as he relives the Hyde Park experience - from inviting friends and sometime playmates Queens Of The Stone Age (‘the greatest band in the world’) and heroes Motorhead (‘a dream come true’) to support them, to performing to an audience the size of which ‘I’d never seen before’ and having Brian May and Roger Taylor from his all time favourite band Queen join them on stage for a quick romp through Tie Your Mother Down - confirms that it really was a big day for him.

‘Meanwhile, I’m backstage in our dressing room area, barbecuing for friends,’ he adds like it’s the most natural thing in the world to be doing before the biggest gig of your life. ‘Before I went on I was on the grill, making stakes and chicken for everybody. So it didn’t feel like the most important show of our career. It was more like I was hosting a barbecue of 85,000 people. Seriously, it just felt like the biggest party I’d ever had.

‘And again with Live Earth. I walked on the stage and thought, “OK, this is a fucking massive stadium, we’re on between the Pussy Cat Dolls and Madonna, I’m not sure if we belong here right now.” Then the audience starts signing along like this choir, and it’s amazing. It feels completely natural. I’m not the type of guy to go sky diving or Bungee Jumping, but I don’t mind strolling out in front of 90,000 people and singing a song about love.’ 

He pauses his beard smoothing as if to properly contemplate the ludicrousness of what he’s just said. ‘I never imagined I’d be comfortable with something like that. I remember, years ago thinking, I don’t know how to be this great entertainer, this larger than life frontman.’ He lets out a tired, self-mocking laugh and resumes stroking his hairy jowls. ‘Then I realised that’s not the point. Just get out there and play.’

It’s rare and refreshing to find someone as successful and famous who’s so utterly content with life. Even drained and exhausted he exudes an enthusiasm that says he’s having a ball, life is good and, sleep aside, he couldn’t ask for more. But then Dave Eric Grohl doesn’t conform to any of the clichés of fame and fortune.

He’s never had any Class A habits - his drug intake being limited to being ‘a miserable pothead’ in his teens. Coffee, cigarettes and the odd whiskey are his only current vices. Likewise, there’s no revolving door on his hotel room – he’s happily married to second wife Jordyn, a former MTV producer, who he recently had a daughter, Violet Maye, with.

Grohl doesn’t do red carpets or awards, unless he’s nominated or performing. He doesn’t hangout in ‘celebrity’ bars and restaurants, and apart from former girlfriends - Hole bassist Melissa Auf der Maur and, according to Hollywood gossip, Winona Ryder – his only famous friends are Queens Of The Stone Age and comedy actor/Tenacious D singer Jack Black, both of whom he’s played drums for as one of his many musical side projects.

‘I just don’t think we get off on being celebrities,’ he fires back almost defensively at the mere mention of the ‘C’ word and the insinuation that he and his fellow Foo Fighters - guitarist Chris Shiflett, bass player Nate Mendel and drummer/ladies favourite/comedy sidekick Taylor Hawkins - actively avoid playing the fame game. ‘We get off on being musicians,’ he adds with a considered chin stroke and a pointed look, just so we’re clear.

The absence of rockstar behaviour and celebrity leanings, along with his contentment with all of the above, Grohl attributes to the two things which have shaped his entire career: low expectations and a complete lack of ambition.

‘Everything that’s happened, has been an accident,’ he says with an it’s-true-it’s-true nod. ‘From playing in bands as a teenager to the success of the Foo Fighters, everything’s just happened. You know, playing hardcore punk in the ‘80s in Springfield, Virginia, there was absolutely no career ambition because there was no career in making two minute long, 200 beats per minute, hardcore punk rock songs. We just did it for fun. Starting a band, practising in a basement, pressing our own singles, making our own fanzines, going out on the road, booking our own tours… it wasn’t a career option. You were lucky if you got your $7 a day living allowance and if you didn’t, then you just had to steal food.

‘It was the same when I joined Nirvana. We signed to a major label, but we had no idea that that was gonna happen. We had no idea that we were gonna sell millions of records. We knew we had good songs and that we were going to make a decent album, but none of us, not even the f***ing record company expected that sh*t to happen.’ Indeed, Geffen Records originally hoped that their new signing’s 1991 album, Nevermind, would sell 250,000 copies; eventually it sold 9 million, and continues to sell, on average, 150,000 copies a year.

‘So when it falls in your lap like that, you just kind of chuckle. You look at it and go “What the f**k? That’s insane”. I was able to make my way through that whole situation by sort of holding it at arms length and thinking, “Now isn’t that strange? Who’d a thunk?”.’

Even so, the lack of a career plan is no guarantee that success, when it comes, won’t go to the head. Most rockstars aren’t born demanding the banishment of yellow M&Ms and the bowing and scraping of minions.

‘But our attitude was shaped by the underground punk rock scene that we all came from. There were no rockstars in our scene. We had musical heroes, but everyone was considered a human being and entirely approachable. It was anti that rockstar thing. We were doing it for the right reasons. That’s never changed. We might sell a bunch of tickets at Hyde Park, but I still feel the same way.’

As if to emphasis his lack of pretension, he slumps back into the sofa and ends up near horizontal, with his chin resting on his chest. ‘I think that attitude’s had a lot to do with the band’s success,’ he says, barely able to move his mouth. ‘Even when the Foo Fighters started, it was just a demo tape that I did down the street from my house. I didn’t expect it to be this 13 year career. I didn’t even expect it to be a band at first, it was just an experiment for fun. Not having world domination ambition I think has kept the focus on what’s real which is the four of us making music. It doesn’t matter how many people come to our shows, it’s still purely for personal satisfaction.’

Given his lack of musical ambition, did he ever consider giving up music altogether after Cobain’s suicide? ‘Oh yeah,’ he pulls himself back to the edge of the sofa and lights a cigarette. ‘Oh yeah, absolutely. When Kurt died, my world and my life fell apart. 

‘The foundation of my life was music and it was just pulled out from under my feet. It was heartbreaking just to listen to music. I couldn’t turn on the radio, much less f**king pick up a pair of drum sticks. Then eventually I realised that the only thing that was going to help me through was music, so I started writing and making music on my own. But it was traumatic. It was really difficult to imagine being in a band again. A band is a really powerful relationship between three or four people, and when any band ends it’s a break-up, a death, a loss and it takes a long time to get over something like that.’

As a point of principle Grohl insists on maintaining a dignified silence when it comes to the issue of his and Nirvana bassist Krist Novoselic’s longstanding feud with Cobain’s widow, Hole singer Courtney Love. However, the care with which he speaks about Cobain suggests that the dispute, over who owns Nirvana’s backcatalogue - during which Love filed a court injunction to stop the release of a boxset to celebrate the 10th anniversary of Nevermind and sued Cobain’s former bandmates, claiming that they were hijacking Nirvana’s legacy - must have hurt. 

While not prone to making a public show of his feelings, save for those aimed at George Bush, musically Grohl does give odd clues as to what goes on behind the goofy grin. As well as plenty of stadium scream-alongs on a par with raging first single The Pretender, new album, Echoes, Silence, Patience And Grace, contains intimate moments of an intensity not seen previously on a Foo Fighters record. Specifically, closing piano ballad Home, comes with such tangible sadness, that it will choke all who hear it, despite the typically cryptic lyrics.

After laughing off the suggestion that they set-out to make a more ‘grown-up record’ with ‘we just picked the songs we thought were the most powerful, some of the ones we didn’t use were just too nuts,’ Grohl’s momentarily lost in thought, twirling the ends of his moustache into Salvador Dali style handlebars. ‘I guess I’m just not afraid anymore. There used to be things I’d shy away from saying in songs, but not now.

‘The other day I was taking my wife and daughter to the Airport and Neil Young’s The Needle And The Damage Done [a chokingly poignant song at the best of times] came on the radio and I couldn’t listen to it. I had to turn it off. That’s what I hope a song like Home does. It’s a direct connection to someone’s emotions. Even I can’t listen to it sometimes.’ He looks like he’s about to deliver some deep insight into the real Dave Grohl, but before he can expand on the point, the glazed expression clears and comedy Dave’s back in the room. ‘That’s why it’s the last song on the record,’ he falls back into the sofa laughing. ‘Can you imagine it as the opening track?’

With the grin firmly back in place, and the coffee and cigarettes having clearly worked their magic, Dave Grohl is wide awake and back contemplating the secret of his success.

‘I get kids coming up to me and saying, “Hey Dave, got any advice for someone trying to make it?” and I say, “Don’t. Don’t try and make it. If you love making music, make music and if it’s great music people will listen”. It’s not rocket science,’ he chuckles to himself, while putting the finishing touches to his Dali handlebars. ‘I mean, had this never happened to me, I’d probably still be happy. I can’t imagine I’d be disappointed, because I still don’t feel like I deserve it and I sure as hell don’t expect any of it. I never did. So really, all this is just like the cherry on the f***ing cake.’