It's been two hours since Kay and his band came off stage, having treated 18,000 people on Clapham Common to the full-works Jamiroquai live experience. Their first London gig in four years, it was an exhausting two-and-a-quarter hour run through their disco-funk hits, ending with the Godzilla soundtrack tune, "Deeper Underground" and a sea of bodies, following Kay's lead, pogoing in unison to the bass-heavy thud - much to his obvious delight. Kay's in no mood to leave and is talking at warp speed, reliving the experience like an excited teenager who's just been to his first concert.
"Two-and-a-quarter hours," he laughs, grabbing my arm. "Two-and-a-quarter hours. No one can say we didn't put on a show." He shakes his head, while trying to light a cigarette and balance a full-to-the-brim wine glass. "You've got to get it right in London. This is home. Seriously, you've got to get it right. Get it wrong and ..." he shoots a look that says it doesn't bear thinking about. "I was in bed by 10 last night. I had a little kip this afternoon as well, just to be sure I was at my best." He stops trying to light his cigarette and winces as his stretches out his left leg. "I'm not sure my knees are at their best though. Still, I'm not 18 any more."
He's beside himself that so many people recognised the tracks from Jamiroquai's 1993 debut album, Emergency On Planet Earth, and that the new material "went down a treat". He's not convinced that they were loud enough and they had to finish too early - local authorities imposed strict volume restrictions and a 9pm cut-off. But all in all it was a good day. Especially when the sun made its only appearance of the afternoon for the jazzy sway of the new single "Seven Days In Sunny June". "Did you see it? Right at the end. Just for the last chorus..." He looks transfixed for a second.
If Kay seems pleased with himself, it's for good reason. Later, he'll admit, in a rare vulnerable moment, that he didn't think he'd make it back here. He'll confide that the four years since Jamiroquai's last album, A Funk Odyssey, have been "difficult" to say the least; that his lifestyle took its toll. And he'll say, with a fixed stare that confirms that for once he's not joking, that he came close to throwing away everything he'd worked for in the 13 years since he first introduced the world to his Seventies grooves, contortionist dance-moves and extensive hat collection. But for now he's just contagiously happy.
"And it didn't rain," he shrieks, shaking his head, still trying to light the same cigarette. "I thought it was going to at one point. I thought, Bloody hell, typical, biggest gig in years and it's going to bloody rain. But it didn't. Fantastic."
THE FOLLOWING week, it's a very different Jay Kay waiting at the end of Horsenden Manor's winding gravel drive. Dressed head to toe in black, he looks business-like and purposeful; every inch the self-assured 35-year-old, whose single-minded determination has seen him sell 20 million albums and swap a squat in Ealing, west London, for a 72-acre Buckinghamshire estate, complete with meadow, trout lake, recording studio and race-track.
The 300-year-old estate is the perfect retreat for an ecologically minded multi-millionaire with a serious car habit. Calm and serene, there's nature, green and lush, by the mile, and garage space to match. The gleaming black £500,000 Ferrari Enzo, the Aston Martin DB5 and Coco Chanel's stretch Mercedes, highlights of one of the world's most enviable private car collections, remind you that their owner is one of the last of a dying breed: the genuine rock star.
Today though, the cars are staying in the garage. Kay has only just got his licence back after a six-month ban for speeding - his fourth - and he'd like to keep it a little while longer. In any case, it's clear that he's not in the mood for living up to his wild reputation. Perched on a beaten-up leather sofa in The Chequered Flag - every country estate needs its own fully functioning pub - he takes a sip of coffee, lights a cigarette and gives a nod that he's ready to talk. And he needs little encouragement.
"How am I?" he says. "Well, I'm a reasonably healthy boy now actually since I stopped doing Class A drugs." He pauses to take a drag on his cigarette and make sure that the news that he's finally conquered his longstanding cocaine habit has been duly noted. "I've been clean for a year and a half now. I've got control of my life back. I had to say enough is enough."
But not for him the celebrity rehab route. "I wasn't going to check into The Priory," he says dismissively. "Sit around with a bunch of other people and talk about my 'situation'? Forget it. No, the bottom line was to just stop. I got one my best mates, Ollie, who's done everything and doesn't do any of it anymore, to move in for a year to keep an eye on me and on 1 January 2004 we just plunged ourselves into it. Out running in the freezing cold, getting fit, working on the new album, anything and everything to keep me away from it until such a point where there's no going back, because to go back is to betray yourself."
The account is typical of a Jay Kay story. Fast-paced, uninterruptible and driven by a mind-over-matter attitude to adversity. Yet the bravado undersells the seriousness. "People do have relapses," he adds carefully, aware that any claim to unyielding willpower may some day come back to bite him. "I haven't had one and I've no intention of having one, just because I believe that my luck's changed now and my life's getting better."
For all the headlines and pictures of him making the most of his playboy status on the London party scene, Kay claims that he's never actively courted that kind of publicity. As far as he's concerned, he's a successful musician, not a celebrity - "I don't even like using the word." Like it or not though, that's what he became during his three-year relationship with the TV presenter Denise van Outen and he's endured a fractious relationship with the media ever since, culminating in the infamous incident in 2002 when he was headbutted by a photographer.
Talking about that incident brings about a sudden cooling of his positive energy. "They're a pack of rats," he snaps, jumping to his feet to pace the length of The Chequered Flag's bar. "I'm no shrinking violet. If they push my buttons, they're gonna get it. But perhaps I was more up for it then. Now, I can't be arsed." He drops back down on to the sofa and the bravado slips for a moment.
Talk to Kay for any length of time, on any subject, and it's hard to miss an ever-present sense of paranoia. According to him, the local constabulary make it their business to catch him speeding. The paparazzi are out to get him and as for his record company, "Well, let's just say, I never, ever, forget that we're not friends." His deep-seated mistrust of people and their motives is drawn from his own experiences, and also those of his mother, Karen Kay. A successful jazz singer in the Seventies, she instilled in her son his love of music and a tireless work ethic. But seeing her swindled and mismanaged made him both professionally and personally wary.
"I am very cautious of who comes into my life. Very cautious," he reveals, with a faint note of sadness. "I've been stung a few times, by people I thought were friends. You've got to be careful who you're dealing with, you've got to know that people want you for you, and not for all this," he says motioning to the manor, the cars and the acres outside the pub window.
Though an inevitable by-product of success, his suspicious nature makes relationships of a romantic nature particularly problematic.
"I'd love to settle down, but it's just finding somebody," he gives a quizzical look and asks if I know anyone suitable. Sadly, I don't. "But seriously, I feel like one of those little weaver birds, that's made a beautiful nest," he motions again in the general direction of the house, "and now wants to share it with someone. I'd like have kids too. It's quite important to me to start a lineage, have somebody to leave all this to." Not wishing to sound sorry for himself he quickly adds that he's enjoying the single life, but if the right person came along ...
"And I'm more ready to settle down now, because I don't do Class A drugs anymore. You're never going to find the right person when you're in a state like that, and I had become a state." So what's he looking for in his ideal mate? "I'm quite old-fashioned really. I'd like to be able to look after somebody, cook them a nice roast dinner, go for long walks." He flips another cigarette in his mouth and breaks into a sly grin. "I just want what everyone else wants really," he says. "Someone who makes me laugh and is quite naughty in the bedroom."
After a whistle-stop tour of the archetypal rock-star house - the James Bond-set living room, the Venetian dining room, the cinema, the gym - Kay leads the way through the grounds, en route to the trout lake.
"There are two very different sides to me, and this is what people just don't get. I'm either a hundred miles an hour or ten miles an hour." He lowers his voice to prove the point. "I can be very quiet at times." If anything, there are three sides to Jay Kay. There's the frantic, over-excited force of nature, the entertainer who barely pauses for breath. There's the nature-loving romantic who points out the different trees - the maple, the birch, the oaks - as we make our way across the estate.
And then there's the single-minded, determined scrapper who stops at the edge of the lake, takes a deep breath and says, "I don't think I'm a simple person to understand. You've got to remember, I've come up to where I am from nothing, absolutely nothing." He stares into the middle distance. "I've worked for all this by myself and it's been hard work and a lot of stick and a lot of graft and a lot of fun. And it's paid off."
He turns, takes in the view of the house and grounds and puts a firm hand on my shoulder, to make sure I'm paying proper attention. "This is a fucked-up business and you can go down with it. But that wasn't going to happen to me. I had a lot people who didn't stick the course, who thought the ship was sinking. And that's fine." Releasing his grip, he lights yet another cigarette, exhales and cracks another sly grin. "But hey-ho, I'm back and back with a vengeance."
The single 'Seven Days In Sunny June' is out on 15 August. The album 'Dynamite' is out now, both on Sony BMG