The Quietus finds itself in the small yet busy office of Bob Geldof's management company near Chelsea harbour on a damp, late January morning. The buzz that fills this relatively small space is palpable as phones ring, diary dates are filled and rejected, and somehow - in this controlled yet faintly chaotic hubbub - a room is prepared for our imminent meeting. Sir Bob Geldof is running a little late. 'Battersea Bridge is always a nightmare at this time of the morning,' apologises his PR, shortly before revealing that his wife has threatened to leave him if he makes good on his desire to celebrate his 50th birthday by tattooing the word 'Earl' on his right forearm and 'Brutus' on the other.

The reason that The Quietus is here waiting is that pop's very own Nelson Mandela is about to release his fifth solo album: the self-consciously titled How To Compose Popular Songs That Will Sell, which will be his first LP since the highly personal collection that was 2001's Sex, Age and Death. Given Geldof's towering profile as the driving force behind Live Aid and Live 8, his media interests and additional campaigning for the father's rights movement, it's all too easy to forget that the man who clashed with prime minister Margaret Thatcher over the VAT levied on Band Aid's 'Do They Know It's Christmas' first started out in music - initially as a music journalist in Vancouver and then as frontman of Ireland's answer to punk, The Boomtown Rats.

Similarly, beyond that band's smash, 'I Don't Like Mondays', most people struggle to recall that The Boomtown Rats regularly visited the UK charts of the late 70s and early 80s with a frequency you could set your watch to, with hits such as 'Rat Trap', 'Looking After Number 1', 'Mary Of The Fourth Form' and 'Banana Republic'.

To be fair to Geldof, How To Compose Popular Songs That Will Sell is far from the dog that knee-jerk ridicule would have you believe. Reflective in nature and far from the bile one might come to expect from this most forceful of voices, the album is much like the man himself as it speaks in a number of voices ranging from the Beefheart-influenced of 'Blow Fish' through the folk-inflected 'Mary Says' and the country tinges of 'Here's To You'. But after nearly a decade away from making music, one wonders what Geldof's motivation is for putting out an album so far down the road after his last effort, and just what it is that he's trying to say.

When he does arrive, Geldof doesn't disappoint. Beyond a few tell-tale marks on his neck, the tall and trim Geldof could easily pass for a man a decade younger than his 59 years. Possessed of a full head of hair and attentive, seeking eyes, Geldof sits down with a strong black coffee and it soon becomes apparent that he's more than aware that the odds are stacked against him in terms of how his work is perceived and what he hopes to achieve with it. But when pressed on Live Aid's legacy and the role of pop and how it relates to the outside world, Geldof has very specific ideas.

What's compelled you to go back to the studio after nine years?

Bob Geldof: Well, I play all the time but just not here because I can't get arrested. The sum of my ambition is to play a 2000 seat venue in London. If I could do that and sell it out, I'd like that but that's not possible and I know that. That doesn't come with any bitterness. If I could I'd just get in the car, play with this fantastic band to a good crowd of people, be deeply satisfied and then go home and have a good night's sleep.

Does it frustrate you that your music isn't judged on its own terms and merits?

BG: Frustrate is maybe the wrong word. I can do stuff anywhere else but here, because the other stuff that comes with me I don't really carry around with me in other countries.

The reviews for it have been nice. I was doing it for Chris Evans' show live from my hotel toilet in Paris because I didn't want to wake the wife, and he was going, 'This is great, it's such a surprise!' He was genuinely glad for me and I'm thinking well, why are you glad? The last record, I thought, was fucking great - but of course the gap between records has been so long that when you decide to come up with something eight years later, you get constantly damned with faint praise.

You think to yourself, well it's OK this record, they're a fucking good band, the music is fine, and the lyrics are OK. Stop talking about The Boomtown Rats because guess what? It was 30 years ago. I'm very proud of it and if you want examine it in the context of what this guy does then that's absolutely valid, then you can have a quick listen to some of the solo things and that'll give you a handle on what I do. But that's too much to expect. When I reviewed albums, I didn't fucking do that at all.

The album, like you, comes from many different directions. Where are you coming from and what are you trying to put forward?

BG: I don't know. It's an impulse and the impulse becomes an urge and the urge becomes the cathartic endeavour. You don't know where the impulse comes from but you are aware that there's something going on

In my case, the impulse isn't driven by any commercial need; it's not driven by any desire to be in any way in the charts because that thing has gone. I don't consider the charts. I don't look at them, they just don't interest me at all. And it's odd because that was it back in the day. We'd go to the label and go, 'How many tickets are we selling? Is it more than The Clash? Did we sell out faster than The Jam?' It was that! And I know people still like that. George Michael is still like that; he's fascinated by pop music and he listens to all of it. He says, 'Did you hear that?' and I just could not give a wank.

But what are you trying to do? Weller has decided to explore different kinds of music while Robert Plant has decided to mine his roots. Your album is very diverse and it strikes me that it's only on the last three tracks that you find your voice.

BG: No, no, no. I'm not Paul Weller; I don't sit in a studio with a band. I go out and do other shit because it interests me and because I can do it, and maybe if I'd focussed intently on just the music that would have been it, but I can't keep doing the same thing. I can't keep doing the politics, I can't keep doing the business – it bores me if I just stay there. It's just a magpie thing.

Is music as a cultural force for change a dead end?

BG: Yes. I think it turns out that rock & roll was a 50-year pop. And that's sad for people of our generation. Pop culture now is ubiquitous. We're heading into a shitstorm economically, and the only upside is that perhaps the need to articulate that will emerge through some outraged children, and then there will be a vitality injected back into British music. I really hope for that, not that people suffer as a result of this mess.

Creatively, Britain is the only place to be in the world. I'm a Paddy and I could live anywhere but I choose here. Let me be specific: it's London, and this constant culture of ideas that permeates and cross pollinates, and it's very exciting to be around it. To observe all that politically, or to engage in it musically, is exciting. And I need to be excited a lot because otherwise I get into a state of melancholy, a palpable emptiness.

I've always only been able to relate me and an idea of the world through pop – that's it. It's been like that since the age of 11 since I heard Radio Luxembourg in this not very nice life. Suddenly these young men and women were articulating not only the possibility of change and its desirability, but also its necessity. And they demanded change now, and it's going to happen anyway, so you may as well be engaged in that. That's absolutely what happened. You're looking at Ireland with a zero economy, this little island way off the western shores of Europe. Totally isolated. That was my musical eureka moment.

From then on - pathetically, but I make no apology for it - I can only frame my experience through the vernacular and the language of rock & roll.

How do you view your legacy? It seems that post-Live Aid, very few artists have anything to say anymore. For example, Britain invaded Iraq yet the voices of dissent were few and far between.

BG: I think that specific politics are a bore. Red Wedge was a joke. It was so old hat they may as well have been in the 1920s with no concept of what modern politics was about. The only one I've got a lot of respect for in this area is Billy Bragg, who has an idea of politics that he's utterly true to and maintains it with great integrity and makes fantastic music. He sees himself clearly in the Woody Guthrie vein, but for me it's very old hat. It's like a Depression-era romanticism with no basis in reality. So a pop band getting up to protest against Iraq is as relevant as a million people protesting against it. Nobody pays any attention.

Forget protesting. Forget marching around Trafalgar Square singing, 'We Shall Overcome'. It fucking gets you nowhere! So get real. You want to stop something then put your guitar down and engage. Otherwise fuck off and make a hit record. You either stop and engage utterly or don't do it all because we can all write a nice little song like 'Give Peace A Chance' because music does not change things.

No, but music can at least create a debate or present a scenario that's been created by outside forces and act like a bulletin. Take for example something like Kenny Rogers' 'Ruby Don't Take Your Love To Town'. It's not explicitly about Vietnam but it came out in the late 60s and it is about a soldier coming home and the impotence caused by his injuries sends his wife looking for physical love elsewhere…

BG: When you're reduced to actually being specific… the whole joy is when you haven't a clue what's going on. I'm so engaged in the empirical – business, politics – and that only works incrementally. You can't go from here to the ideal – they [the politicians] won't do it.

So I'll say, 'OK, what will you do? Will you go there?'

They'll say 'No.'

I'll say 'Why? OK, maybe we can get to here.'

'Yeah, OK. I can carry that.'

That's empirical negotiating the whole time: finance, economics, empirical negotiation.

Live Aid was not a cultural event. You can shove your rock & roll debate up your hole. It was a political lobby. It was entirely empirical. It turned out, much to my dismay, that it had a greater romantic resonance than I had anticipated. I wanted an organisational continuum and I wanted a political lobby to elevate what I thought was a serious global issue: poverty. More than half the world live on less than $2 a day and the economic logic of that with the globalisation that was just beginning – and Live Aid was an avatar of that by using the international language that was not English, but rock & roll – and you could suggest an idea of change. Not articulate it, but suggest it.

My idea was the entire panoply of rock & roll. So here's the entire history of this cultural force for change which arose from that political and economic necessity but all you really need to hear is, 'A wop bop a loo bop a wop bam boo!' That articulate scream of rage until you finally nail down, They'll say 'Hello. What are you trying to say beyond that shout, which we perfectly understand?' What I'm trying to say is, 'Don't step on my blue suede shoes.' The politicians will say, 'What do you mean?'

I'll reply 'Well, first off, I've got suede shoes so fuck off! They're blue; I'm a little out there. Don't fuck with me. Don't step on them.' It's all hidden metaphor and it's fantastic so Live Aid was that; it was just a suggestion – here we all are. Can we change this? The fact that 30 million human being may die through hunger is ridiculous, and to die of want in a world of surplus is not only intellectually absurd, but morally repulsive. So I don't care who is on the fucking bill because if it was me, it would be John Lee Hooker, Van Morrison and The Boomtown Rats. It doesn't matter who is on it: can you drive through to a conclusion that you can actually make the Body Politic go, 'Fuck! We can't let this happen.'

This can only be resolved through politics. If you want to engage in that, you must engage with the agents of change and the agents of change in our world are politicians. Some choose to stand outside the tent pissing in and some choose to stand inside the tent pissing out and I long ago chose to stand inside the tent and piss. And by getting to Number 1, you set the benchmark by what pop music is at that moment.

See, The Ramones' 'Blitzkrieg Bop' was just as much about the idea of fundamental change and that idea still stays with me, but saying that you've got to engage by writing songs about Iraq or specific issues is a nonsense. It doesn't work. Dylan got sick of it after six months and moved on and wrote songs that had a more profound impact. You just wait - give yourself 10 years and you'll hear the good stuff of today because good songwriters are just intuitive and this country because of the social tectonic plates are constantly grinding and more so now because of this coming fucking shitstorm will throw up people who will absolutely deliver. Pop is an incredibly powerful minor artform. It can sum up, by osmosis, a social period of activity.

When I heard 'Down By The Jetty' by Dr Feelgood I thought, those cunts! That's what I'd been trying to arrive at. A brilliant re-interpretation of primal music coupled with words that were pertinent to me. And that same afternoon I heard Bob Marley fuck with words. They were very different but they were both doing revolutionary music. They both made demands but they weren't specific. It was like 'Anarchy In The UK' – it wasn't specific but it did say, 'You promised me a future if I did your shit but there is no future. Fuck off!'

The fundamental job of an artist is to articulate what society is thinking before society even knows that it's thinking it and when society hears it, it says, 'Fuck, yeah! What's that!' and that's a hit!

I can say that any way I can on television. I will say it and in some way I will make people move the agenda, certainly with Africa. What I can't do is sing about the stuff or articulate stuff that is far more important to me than the empirical or the business or the politics or anything else and that's where the impulse and the urge comes.

I know this is going to look cuntish, but this stuff [his album] is like a self-addressed postcard from my psyche. I only know what it is when I hear it back.

If you had to write your own epitaph, what would it be?

BG: 'Why? Why does it have to be like that? Why can't it change?; Things are not immutable. Things can change, and they should be changed.