Some of you may be too young to remember when Gilbert O’Sullivan shared the limelight with The Beatles. To clarify for the under 30s: Gilbert O’Sullivan is the dude (an Irishman, would you believe it) who wrote ‘Nothing Rhymed’, ‘Alone Again (Naturally)’ and ‘What’s In A Kiss’, famous radio songs that you’d want to have been living in a vacuum to have missed.

Now you know who we’re talking about, you’ll understand my excitement in meeting this musical legend, a man whose singles and albums dominated the Irish, UK and US charts throughout the early 1970s, earning their creator huge fame and fortune by his mid-20s – until fate conspired to pull the plug on his success.

This - on the surface quintessentially English - pop singer, whose real name is Raymond, was actually born in Waterford in 1946. His mum ran a sweet shop and his dad worked in a meat factory. Like thousands of Irish families, the O’Sullivans emigrated to England in search of a better life. Hence, seven-year-old Raymond found himself growing up in a Swindon council house, attending Swindon Art College and playing drums, guitar and piano for various bands as well as writing his own music.

A move to London in the late 1960s brought O’Sullivan his major break. Ex-pop singer/songwriter Gordon Mills took the young Irishman under his influential wing, becoming his manager, song publisher, producer and older brother/father figure. Having guided the careers of Tom Jones and Engelbert Humperdinck, the wealthy Mills was an enormously powerful patron, and from O’Sullivan’s home-base on Mills’ huge estate, the two launched a four-year period of runaway international success.

An infamously bitter split and courtcase between Mills and O’Sullivan turned the artist’s career from the dizzy heights towards a steep decline from 1977 onwards. While he stuck diligently at his songwriting, O’Sullivan found much of his time over the next decade and a half taken up by gruelling legal proceedings – arguably to the detriment of his work as a recording and touring artist, but precedent-setting for musicians’ control over their business.

A Scruff At Heart, Gilbert O’Sullivan’s new album, covers a characteristically wide range of concerns, from school bullying and marital infidelity to the Middle East, and displays O’Sullivan’s extraordinary talents ­– both as a musician and an unusually clever wordsmith – at their best.

Far from being the stick-in-the-mud that the ‘where are they now’ media suggests, Gilbert O’Sullivan’s got some serious wisdom going on. For a start, he looks at least 10 years younger than his three score on this planet. Slim and fit (as befits a man who doesn’t drive), O’Sullivan positively radiates health. How does he do it?

“I keep getting asked that,” he says. “Look it, I’m 60 years of age and I’m really quite happy to be 60. There’s nothing I can do about it so I might as well live with it."

A youthful creative attitude is pretty much the only thing that O’Sullivan has in common with many of his peers and their sex and drugs and rock ‘n’ roll lifestyles (what is it, five different mothers that Rod Stewart has for his seven children?). He’s a regular mass-goer, and is currently working on a song called ‘Once A Catholic, Always A Catholic’, though he says he has a critical attitude to the Catholic church. He only ever drinks the odd glass of wine, and he’s never had a pint in his life (“practically criminal for an Irishman”).

Needless to say, O’Sullivan’s a bit of a recluse. Living in Bunclody for a couple of years in the early 1980s (to avail of the tax break for artists) suited his solitary nature, but made his sociable Norwegian wife feel isolated. Thus the couple’s move with their two daughters (who are now 23 and 26) to the socially abuzz tax-haven isle of Jersey, where they still live.

Huge success in the 1970s led many rock stars down the path of dissipation. What was O’Sullivan’s experience of the temptations?

“Well, the excess was there if you wanted it,” he says. “But I’ve always been a home person. I’m very introverted. Obviously I love my family, but solitude – it’s necessary. That solitary nature is there, so when I was hugely successful, I had my house and I had my pianos, and I could have had what I wanted when I went out. I had the odd girlfriend, but then I wouldn’t let that go beyond just a few dates. I got kind of nervous if they were ringing up more than they should be. I was very into my music, so I was very worried about being taken over by going to nightclubs and getting caught up in all that.

“So that was a really good thing because it meant I stayed home more than I ever went out. I mean, Gordon Mills and his wife wouldn’t have had me babysitting for them [O’Sullivan wrote his song ‘Clair’ about Mills’s infant daughter] if I was jet-setting around the place and going off to nightclubs. I did a bit of that, but not much. The drugs thing, when I was a student, when I was living in London, my flatmates would have cannabis cigarettes and stuff. I tried it like everyone does, but it wasn’t something that left a mark on me, so I dropped it. I’ve always had that… normality.

“And the celebrity thing never appealed to me. There’s a lovely story. Paul McCartney invited me to a party he was throwing in the ’70s for his Wildlife album, and I was pleased to be asked to a big celebrity bash being held in The Lyceum in Leicester Square. I took my sister because I didn’t have a girlfriend at the time. And when we arrived in the taxi, there were crowds of people. It was a red carpet entrance, and I was absolutely terrified. There were photographers and people filming. So I kept telling the driver to drive around. He said after about the 10th time that we can’t just keep doing this. So I got him to pull up just before the place, then I sneaked with my sister up to the top of the queue and barged in with my head down.“

Being Irish-English is clearly something that O’Sullivan’s thought a lot about. (One of his albums is called Irlish.)

“I’m very proud of my Irish roots,” he says. “I love coming over. The draw is there, it’s remained intact. It’s part of me, but on the other hand I see myself in terms of lyrics as English, very English. I’m an English lyricist, yet I have that Irish background. So there’s kind of a contradiction there, which is a bit odd."

O’Sullivan grew up at a time when it could be pretty heavy duty for Irish people in England…. Did he come across any discrimination?

“I’ve seen documentaries where you get no blacks, no Irish and no dogs,” he says. “But I never grew up with that.

“I do remember in the ’70s though, when Mountbatten was killed, thinking ‘Jesus, I’m gonna get stones thrown at me on the street.’ I also remember during my court case there were bombs going off in London. There was a sense that here’s an Irishman suing an Englishman. That was the only time I was worried.

“The one thing I find strange is that when I was doing a concert in Dublin [his debut in The National Stadium], there was chaos here. Bloody Sunday. Maybe because I was caught up so much in huge success at that time I was just oblivious to a lot of the stuff that was going on in Ireland. I wish I had been more aware around that time, because I might’ve been writing about it.”

O’Sullivan’s court case against Gordon Mills was to prove hugely rewarding but also punitive. While the artist won the rights to all his own songs and the recordings of them (a legal precedent subsequently utilised by Elton John and Sting) it was also a horrendously painful experience.

The hostilities began when O’Sullivan, seeing his success begin to drain away, expressed dissatisfaction with Mills’s work as his manager/producer.

“I wanted to work with other producers. And he was horrified. He felt it was a stab in the back ten times over. There was a clique of people of people around him, a world of its own, the lawyers, the accountants, they were all in the brace. So he said, 'Well look, if I can’t produce your records in 1976, then that’s it.' And that strong. His attitude was, you’re financially secure, don’t worry about it. Go away and have a drink and take your girlfriend out. It’ll be all right.

“And I’m thinking no, it isn’t going to be all right. What about my music?

“It was a desperate decision to have to make after all he’d done for me. To have to break up. It was almost like a family break-up – that traumatic. He was almost like a father figure. I might’ve been 21, 22, but I was very immature and naïve.

“I wanted to be successful, despite all the success I’d already had. That’s in me. But he couldn’t understand that. So naturally when we broke up I asked would I still get an interest in my songs? As he had promised. And he said of course you will, speak to the accountants.

“A week later I did and they all knew we’d broken up, and they said, you know… two fingers! It was devastating. All the lawyers that I’d worked with, all the accountants, everybody that I’d worked with on my finances, they were all in on it.

“I walked out of that as bitter as anybody could be. It was a huge betrayal. So I went to court. And I was given a lot more than I was looking for. Because a whole can of worms was revealed. Suddenly my lawyers are discovering very bad deals. They’re discovering non-payment of royalties.

“They discovered it, and they used that as evidence against Mills. My first two years of success, I was getting £10 or £15 a week, which is all I asked for. But the books showed the large amount money you were earning, and you’d see almost 98 per cent of it disappearing in tax. So I’d come back quite depressed. I mean, after two years of worldwide success…. But I wasn’t worried and I wasn’t concerned, because all I ever cared about was the music side of things.

“So the court case revealed all of this. And when Mills was in court, they destroyed him. It was the saddest thing you’ve ever seen in your life. His family… everything about it was terrible. But it could’ve been avoided. All he had to do was fulfil his promise. All they had to do was give me my interest and I would’ve walked out not worrying about anything else. ”

After the court case, Gordon Mills’s company went bankrupt, though he continued to manage Tom Jones until his death the late ’80s. How did O’Sullivan – who eschewed glorying in Mills’s downfall – feel when his one-time mentor died?

“It was very sad,” he says. “I hadn’t met him. But I’ve always given him credit for what he did for me. He was responsible for my initial success, and I owe him a great deal. Especially because he didn’t like my look, and still he was prepared to go along with it. He could’ve been made a laughing stock, people saying how could you mange somebody dressed like that? Particularly because he had these two superstars, Jones and Humperdinck, in tuxedoes.”

The ‘look’ O’Sullivan refers to is clearly a sore point. Comprising a grey-flannel short-trousered suit, flat cap, schoolboy tie, football socks and hobnail boots, the image was not considered cool.

“You wouldn’t have liked me as a student,” admits O’Sullivan. “You would’ve liked the song, but you would’ve found it difficult to walk around with the album under your arm with me looking like that.

“I regret the credibility crap that’s attached to looking like that. It does surprise me that almost 40 years down the line that’s still there. I don’t get angry any more when it gets thrown in my face. I accept it, but I’m kind of confused as to why it’s happening. Because I don’t know what relevance it has today. Is anybody really that interested?

“It’s a bit like if McCartney was being talked about because he used to have a Beatle haircut and wear a jacket with funny collars. It would be obscene, absurd, to hear people talking to him like that now.”

Did it hurt you?

“Oh, it seriously did.”

O’Sullivan had another precedent-setting legal victory in 1992, when US rapper Biz Markie sampled him without his permission.

“All it needs if someone wants to sample your work is that you give them permission. After my court case, if they do it without permission they’re in trouble. This Biz Markie guy was a huge star, and he said we don’t care, we’re doing it anyway.

“They sent it over to me and I didn’t like it. They’d sampled the intro of ‘Alone Again (Naturally)’. I didn’t like it because ‘Alone Again (Naturally)’ is a serious song, and he’s a funny rapper. My song was huge in America and means a lot to Americans. No comedic use can ever be made of that song. You’ll never see it on washing machine ads.“

When we get on to politics, the reason for O’Sullivan’s reclusiveness becomes apparent.

“Oh, I think we’re the scum of the earth,” he says calmly. “I think we’re terrible. The way we’re destroying the world. That’s why I feel the Middle East is so crucial. I really do believe that if you solved the crisis between Israel and the Palestinians, that would make a far more peaceful Muslim world."

Ever the rebel – albeit a square one in terms of the rock ‘n’ roll lifestyle – O’Sullivan’s parting remark shows how little he cares about toeing the party line.

“The Middle East is an issue that young people everywhere should be on. That’s where the Geldof and the Bonos should be focusing their attention. But they’re never gonna do it. Because of their paymasters – they’ll upset their paymasters. That’s my opinion.”