Back in the white heat of the Sixties, just the mention of Dave Clark's name could send teenage girls into paroxysms of screaming hysteria. His band, the Dave Clark Five, had a succession of hit singles between 1964 and 1970, sold more than 100million records, and starred in a hit film.

In America, they were the first band of the British Invasion to tour the country and rivalled the Beatles for popularity. But, unlike Paul McCartney and countless other stars of that era, Clark has been conspicuous by his absence ever since. Apart from a brief flurry of publicity surrounding the hi-tech musical Time, which he co-wrote, produced and directed in the Eighties, Clark has stayed away from the limelight.

Until now. Tonight, BBC Two airs a documentary, Glad All Over: the Dave Clark Five and Beyond, recalling a time when the DC5 were one of Britain's biggest pop exports, and, to mark the occasion, I have been granted a rare interview.

A lot - it turns out - has changed in the intervening years. The figure who greets me at his luxurious home in London barely resembles the athletic pin up of the Sixties. There is a sense of collapse about his features, once thick hair wispily recedes over a stretched pate, a sinking jawline is disguised by a goatee beard. His eyebrows exhibit a curious arch, although he persistently, if not very persuasively, denies suggestions of Botox or facelifts. "Not a thing!" he insists.

What is undeniable is that the 72-year-old Clark has prospered financially. Celebrated in the music industry as an innovative businessman, he was the first rock star to own his own master tapes. He published and produced his own records and managed the band himself. He also bought the rights to pop show Ready Steady Go.

His home is suitably fabulous, cosy yet opulent, comprising several terraced houses knocked through into one and extensively remodelled. It is just the kind of place you would like to imagine a vintage pop star occupying, like Austin Powers with better taste. The décor is cool whites, a mix of antique and modern furnishings, soothing contemporary oil paintings, with all kinds of nooks and crannies displaying golden Buddhas, lush greenery and scented candles.

_{^{All natural: Dave Clark denies having facelifts or botox}}

"I was raised Church of England but I love the Buddhist philosophy, it's very powerful, non-violent," he says. "The trouble in this world, it's envy and greed." There are bronze busts Clark commissioned from Czech sculptor Irena Sedlecká of Laurence Olivier ("I've willed it to the National Theatre when I kick the bucket") and Freddie Mercury, who Clark worked with on Time.

"We were total opposites, Freddie was so flamboyant, but we just hit it off," he says, in the same modulated, subdued tone he discusses everything else. "I was the last one with him when he died. It wasn't planned that way, it was just a small team looking after him, to keep his motivation up. The doctor had left 20 minutes before. I was with Freddie, all of a sudden he just sat up in bed, seemed to smile, and that was it." Clark clicks his fingers. "It was so sad. It made you realise, he could have had anything, but he didn't have his health."

A lifelong bachelor with no children and no known romantic liaisons, Clark's friendship with Mercury has led to speculation about his sexuality. There are photos of Mercury throughout the house, and oil paintings of naked male torsos. But Clark insists he is not gay.

"People make assumptions when you're not married," he says. "I've been best man at five weddings and I said I'd never do it again 'cos everyone got divorced." He seems unperturbed by questions about his personal life. "I've always had a philosophy: it doesn't matter who you love or how you love, the most important thing in life is that you love."

And has he loved? "Oh yes. You've gotta love. Love is the key."

Clark was a working-class north London lad, born in 1942 and raised in the rubble and opportunity of the post-war years, an amateur sportsman (a Black Belt in mixed martial arts) and movie obsessive. At 15, he left school to work as an extra at Elstree, appearing in more than 40 films, including Richard Burton's Beckett and Elizabeth Taylor's The VIPs, eventually graduating to stunt man. "I knew how to tumble, 'cos I'd done unarmed combat. I was fighting on horseback, sword fights, explosions, car crashes. It was all fun. You were young, confident, if you wanted to do something, you'd do it."

The DC5 formed as a skiffle group at his local gym in 1957, a group of friends and Tottenham Hotspur supporters. The line-up was settled by 1960, with the ambitious, perfectionist Clark ruling the roost. "Right at the beginning I said to them, 'It's a bit like a football team, you have to have one captain.'" The line-up featured Mike Smith, an incredible rock and roll singer and classically trained organ player, guitarist Lenny Davidson, bassist Rick Huxley, and saxophonist Denis Payton, with Clark's drum kit to the fore. "I never professed to be a great drummer but I was a very heavy drummer. It was simple but powerful."

By 1963, as Beatlemania gripped Britain, the DC5 were the top-rated live act on the Mecca Ballroom circuit, packing 6,000 people a night into the Royal Tottenham. But when record companies came calling, Clark turned them down because producers wanted to control the material and sound. "I thought f--- it, I'm not going to be put into that bag." So he came up with the audacious proposal that he would make DC5 records independently and lease them to EMI.

His unorthodox methods contributed to the dynamism of the DC5 sound. "There were rules in recording. You weren't allowed to play past where the needle goes into the red. Well, that's bull----, as long as it's not distorting, you can do it. So our records were very, very loud."

They were also very popular, among teenage girls in particular.

"I did fear for my life sometimes," he says with a smile. "We did a gig in Cleveland where a girl jumped out of the dress circle onto the stage and broke both her legs. And still crawled forward to ask for my autograph. It was mayhem."

But, despite their Beatlelike popularity, the DC5 were constrained in a way the Fab Four were not.

"[The Beatles] weren't getting the royalties they should have, but they were given the luxury of a studio for 24 hours for as long as they wanted. As an independent, I couldn't work that way. Unless we got it in three takes I would stop and we'd go down the pub and have a beer."

It's a no-nonsense attitude that might explain why the DC5 never really progressed musically. In 1965, they made a sharp movie, shot with kinetic energy by a young John Boorman, a director Clark discovered and championed, indicative of his true area of interest. In 1967, the DC5 stopped touring and concentrated on television appearances and promo films, which Clark directed himself. They notched up more hits but in 1970, without much ceremony, they disbanded.

"I always said we'd stop when the fun went out of it, that was the agreement from the start. I had other things I wanted to do."

^{Perfectionist: Clark, second from left, ruled the roost}

Some controversy dogs the DC5 because Clark owned the band rights and effectively employed his fellow members, but he insists he "looked after" them well. "We never had one legal letter between us," he says.

In the age of social media, dissenting voices have surfaced, suggesting Clark ruthlessly exploited others' creativity, employing uncredited ghostwriters and session musicians and hoarding the profits. "People are rewriting our history who weren't even born then and never saw us play," he says. "That p----- me off. If somebody's got a complaint, they should write to you about it, or get on and sue the a---off you."

The DC5 documentary conveys the excitement of the Sixties pop explosion. A string of celebrity admirers including Bruce Springsteen, Stevie Wonder and Tom Hanks queue up to proclaim the DC5's impact on their youthful psyches. "Those were big, powerful, nasty sounding records, man," enthuses Springsteen. "Much bigger sounding than the Stones or the Beatles."

But the programme lacks critical insight, perhaps because it was written, produced, directed and edited by the controlling Clark himself. "There's no background story of drugs, sex, raping, driving cars into swimming pools," he says. Although Mike Smith worked as a producer, songwriter and commercial jingles maker until his death in 2008, none of the others continued in music. Saxophonist Payton became an estate agent and died in 2006. Bassist Huxley was involved in property and retail businesses and died 2013. Guitarist Davidson dealt in antiques and taught music and is now retired. Clark gave up music to pursue his first love, studying at the Central School of Drama for four years. "I wanted to be treated like everybody else, get criticised, pulled to bits, I wanted to learn."

Clark never went on to act, but did resurface in the Eighties with his musical Time, which ran for two years in London's West End from 1986-88. Laurence Olivier appeared as a hologram in his last ever stage role. "That was quite an experience. Olivier was the greatest actor in the world and he didn't suffer fools gladly but we hit it off right away." An all-star album, featuring Freddie Mercury, Cliff Richard, Leo Sayer, Stevie Wonder and Dionne Warwick sold over two million copies and spawned four hit singles. But Clark admits he found the film and theatre worlds frustrating. "Being independent and having success, all the committees and compromises involved in that system, it doesn't work."

Today, he runs a publishing company, overseeing the rights of his own music and other artists, including television footage of the Beatles, Stones, Otis Redding and many other Sixties legends. "I miss going out on stage, physically playing in front of an audience; it's like being heavyweight champion of the world for that moment. But everything else that goes with it: the interviews, the travelling, being locked away, I don't miss that at all."

The DC5 never reunited and have slowly faded from pop memory. Yet their mastermind remains a fascinating, slightly inscrutable figure. As Elton John says in the new documentary, "Dave's a man of many mysteries."

"You've got to know when to stop. My greatest example is Muhammed Ali. We were good mates. It's a shame he didn't retire when he was champ. In the end, he went on fighting and got brain damage."

Photos of Ali with Clark adorn a mantelpiece, along with old pictures of his parents and smiling snapshots of Clark and Mercury. Clark may be out of the public eye, but he insists he is not reclusive, with many close friends including Elton John and Ian McKellen. An attentive female housekeeper pours red wine in what appear to be some slightly fancy beer glasses. A black labrador dozes at Clark's feet. "I was devastated when the boys died. We were young kids and it was exciting what we went through together. It makes you realise how important living life well is, because none of us know when we're going to go."

Clark raises his glass. "You can't argue with success.

I'm living in this lovely place but it's not to be arrogant or flashy. I always believed that if you do something well then you will reap the rewards. Me and the boys, we knew what we did and were very proud of it. And that's it. I don't want to live in the past."

'Glad All Over' is on BBC Two tonight at 10pm