Robert Frederick Zenon Geldof — Bob for short — was born in Co Dublin in 1951. He was a journalist before joining the Boomtown Rats in 1975. His 1985 Live Aid concerts raised more than £150m for famine relief in Africa. He has three daughters, Fifi Trixibelle, 21, Peaches Honeyblossom, 16, and Pixie, 14, from his marriage to the late Paula Yates and is adoptive father to Tiger Lily, 8. He received an honorary knighthood in 1986

Nothing about Bob Geldof is conventional: that goes as much for his motors as his motor mouth. He turned up on a motorbike for a recent drop the debt meeting with Gerhard Schröder, the German chancellor. And on his televisual odyssey across Africa he was filmed in a clapped-out Renault estate, remarking that the exhaust was about to fall off (an understatement: the entire car sounded as if it was about to explode).

For our interview the Live 8 organiser and Boomtown Rat draws up at Soho House, a London private members’ club, in a more conventional conveyance: a silver Mercedes courtesy of a limo service, pausing to shoot the breeze with Sarah Brown, wife of Gordon, perched on a sofa amid the tasteful decor. His own motoring tastes are eclectic, ranging from a Jeep to an Alfa Romeo and a Bristol.

The Bristol is an interesting choice: a deeply traditional handbuilt British marque long beloved of buffers, it is becoming the unlikely wheels of choice for rockers: Bono, Geldof’s fellow anti-poverty agitator, and Liam Gallagher have bought them.

The cars are sold for £130,000 upwards from Bristol’s one showroom in west London, where Britain’s last independent luxury car maker offers exclusivity and an understated style that befits the wealthy.

Loosening his larynx in preparation for his G8 concerts, Geldof starts chatting and he can’t help but look back on Live Aid. Though the charity event made him an international celebrity he reckons, paradoxically, it did for his rock career. “The Rats had to put off an album, which was a f****** disaster. We couldn’t be seen to plug it (immediately after Live Aid).” However, he admits that if the band had been doing better before that he would have been busier and “I would not have been home that night” to see Michael Buerk’s Ethiopia report. Then there would have been no Live Aid.

Despite the fawning of statesmen he would rather be eulogised for his music. He affects not to care about status: “I am not a rock star, I am a musician. That is what it says in my passport and that is what I do, 24/7.”

U2 and Queen benefited hugely from their Live Aid performances — more than Africa, perhaps — but the music made by the man who inspired the concert was largely ignored. “I was completely bemused as (my music) was good s***, but intellectually I understood: get out the f****** way and make way for the next thing, like a snake shedding its skin. There is a ruthlessness in pop but it’s hard to deal with.”

He insists his ambition had always been “to be rich, famous and get laid”: “I’d been poor all my life. I come from Catholic Ireland; getting laid is a problem. Suddenly I found I’m in a band and girls want to shag me.”

Despite the bravado there has always been a trace of melancholy trickling through his life. He says he has been in a “veil of gloom” since his mother died when he was seven, which turned him from a keen schoolboy aiming to be a journalist into a sullen, withdrawn outsider.

“My dad was never at home, selling towels around the country, so I brought myself up. If my mum had been there you’d probably have a very neat Bob Geldof with ironed shirts and non-scruffy hair.” Depression, he says, has always lurked at his door and the slightest excuse can bid it inside. But for Geldof the excuse wasn’t slight, it was the death of his former wife Paula Yates. He discloses this nearly drove him to suicide.

“I just made a list of pros and cons and unfortunately baling out was very heavy on the pro side and intellectually I just didn’t want to wake up any more with that pain. Pain isn’t the correct word. All the words are overused: it is unsayable. The one thing opposite it was the children. I called my good friend in Northern Ireland and he said ‘stay exactly where you f****** are’ and he came around and talked me back up.” Geldof looks away. “I ’m ashamed of myself, to be honest with you.”

Why? “That I should even consider it when there were far more important things than myself. Practically everything else is more important than yourself.”

What drew him out of it? “I didn’t want to venture into those realms again. The grief, it was so all-encompassing and my universe was smothered. You’re at your most ugly in your soul; physically you just don’t believe anyone can love you again. Then this beautiful woman comes along and you have your beautiful children: oblivion versus love, I’ll take love!” He is referring to his foxy French girlfriend Jeanne Marine. And for the first time he almost smiles and the veins stop pulsing on his forehead. How is he now? “Not bad. I remember a friend called and said ‘how do you feel?’ I was just about to go ‘shite’ but I actually thought, ‘no actually, I feel okay’. And once I’d said it I thought ‘hang on, that’s new’. I was still making records, still doing gigs, the kids are great, Jeanne is gorgeous; f****** hell, I’ve got some wedge, just come back from Africa . . .”

That is the Geldof paradox: despite his gloom he is an incurable enthusiast. Yes, he remains the Irish curmudgeon but speaks of “the amazing country” that is England with an enthusiasm only an outsider can muster. “It has such unbelievable power and influence, people from all over the world will listen.” His enthusiasm is stoked by meetings with Brown and Tony Blair. “They are Live Aid babies, they endorsed its ramifications.” He enjoys that rock/politics nexus and refuses to feel guilty about his wealth, despite his obsession with another continent’s withering hunger.

He has a country pile — a former priory in Faversham, Kent, estimated to be worth £2m — and a £700,000-plus Battersea apartment.

“I do my bit,” he insists. Geldof remains insecure that he never made the rock super-league, and running a band was expensive, forcing this debt relief campaigner to make his serious dosh through enterprise.

“Album sales weren’t as huge (then) as they are now. There are six guys (in the Rats) and their families and road crew and their families. Ultimately I made a loss.” Members of the band recently threatened Geldof with legal action over alleged unpaid royalties, claiming he owed them money from the 1970s and 1980s when the band’s hits included I Don’t Like Mondays.

Yet Geldof is a shrewd cove and knows his onions. Indeed, he is threatening to perform at next weekend’s Live 8 concert in Hyde Park, even though some rockers of greater renown have not been invited.

He recalls how Sting told him that every day he cranks himself up to pen a few more pop ditties by recalling his past, dull life as a teacher. Geldof feels that keenly too, remaining a phenomenon because he remembers all he has learnt along the hard road. “Dylan taught my head to move, Mick (Jagger) taught my hips and Pete (Townshend) taught my heart.”