In a windowless but well-appointed basement suite of a London hotel – there are drinks and nibbles, and the sofas are plump – I have just asked Sir Tom Jones whether he harbours any major regrets in life. His eyes, which, up close, are pale enough to appear translucent, flash with the sudden effort of concentration.
"Regrets?" he repeats. "No, no. No, I don't think so." But then he changes his mind. "Actually, wait. One night in 1965, I was in this club in Los Angeles watching Little Richard perform. My visa had run out a few days previously, and my manager had advised me not to do anything that might constitute work. Halfway through the show, Richard invited me up on stage. He was on fire that night, and I wanted to help him rip all hell out of that tune, but I didn't. I just stood there, shaking my head, like I was convinced the moment I opened my mouth, Immigration would appear." He shudders. "I tell you, I still think about that sometimes. That's a regret."
And here comes another.
"It was one night, can't remember the year, but I'd just finished a show in America. Elvis," he says, before adding helpfully, "Elvis Presley, was in my dressing-room. Now, Elvis was well aware that people were forever taking pictures of him, so he always made sure he looked his best. Sure enough, somebody soon came up and asked to take a picture, and so there we were, arm-in-arm, Elvis looking all perfect, like, and me..." He waves his hand up around his face, as if to suggest the presence of a double chin. "...I hadn't straightened myself up properly, see? I looked awful. And in that picture, I always will. I bloody regret that an'all." He sighs. "But other than that, no, no regrets."
Little wonder, really, for here is someone who seems, in every sense, to have had it all. Having served out his three score years and 10, Jones has recently tipped into his eighth decade looking remarkably fit and healthy. He confirms this, more than once, by exclaiming: "There's nothing wrong with me! I don't have any ailments!"
He certainly looks more robust than your average 71-year-old, and, in a general sense, remains statuesque: arms like tree trunks, thighs like bigger tree trunks, a wide smile and a voluble presence compounded by his deep, rich voice which fills the room with an almost biblical resonance. He stopped dyeing his hair Dracula-black a few years ago, and thank goodness for that, frankly, because the grey suits him more, as does the physical evidence of his advancing years. Given that he has called California home for the past 35 years now, you fancy he must have had some work done, but it doesn't show. When he says something that causes him to frown, his forehead frowns right along with him.
At an age at which society tends to consign people to the sidelines, Jones is experiencing something of a renaissance. Of course, musically speaking he has been in the middle of a renaissance since 1988, but this is a multimedia renaissance. He now has Saturday-night telly fame – on the BBC1 talent show The Voice – and he has just made his acting debut in a short film called King of the Teds, which aired on Sky Arts last month.
"I've been asked to do things – films and that – in the past, but they were always too cheesy, and always musicals," he says, lip curling in distaste. "Elvis – and I don't want to name-drop too much here – but, well, Elvis bloody hated those things, so I always stayed well clear. I never wanted to be in a movie with a bunch of dancing girls."
King of the Teds, which co-starred Brenda Blethyn and Alison Steadman, did not feature dancing girls. Written by Jim Cartwright, the man behind Little Voice, it was a poignant drama about a man with a natural talent for singing but for whom the cards never quite fell correctly.
Jones felt confident he could deliver, he says, because it was essentially the story of his life: "A fella from a small town, two girlfriends, got one pregnant, and married her. Only thing was, I escaped from the small town, he didn't."
Throughout the filming, he would experience eerie waves of not-quite déjà vu, a parallel universe in which another Tom Jones was condemned to live forever, undiscovered.
"The house it was set in was basically the house I grew up in, in Pontypridd, so it felt very weird. I couldn't help thinking, "There but for the grace of God." It made me feel so grateful that I got lucky. OK, I may have had this voice, but luck was definitely involved. It always was. It still is."
Tom Jones escaped Pontypridd in 1962, and by 1965 was already on the way to superstar status, "It's Not Unusual" spearheading a run of hits that would span the next six decades. Unlike, say, Cliff Richard, for whom fame always seemed to compromise the maintenance of his halo, Jones relished his success and, despite being a married man and a new father, he lived up to his reputation as one of the UK's most virulent men with unstinting enthusiasm.
His musical career ebbed and flowed over the years, as he drifted in and out of fashion. Never a songwriter, he had instead to rely on the strength of the songs that were provided to him. Many of them – "Delilah", "She's a Lady", "Thunderball", countless more – proved timeless, but even the less memorable ones – 1977's "What a Night!", for example, or 1979's "Dancing Endlessly", neither of which make Greatest Hits retrospectives – were emboldened by a voice that, like his friend Elvis's, could breathe life into the most flatlining of rhyming couplets.
By the mid-1970s, he had fallen out of fashion, famed now only – and wrongly, he still insists – as one of Las Vegas's more enduring star attractions. "I only ever played two-week residencies maybe four times a year," he grumbles, "but it was reported like I was always bloody there, and I did get tarnished with a particular Vegas-y image that probably didn't do me any favours."
A decade on, and he was, in effect, history, no more the leather-clad colossus with his own primetime TV show, but rather a singer of syrupy standards that were big in America's country-music charts, and nowhere else. It was only after the death of his manager and long-time friend Gordon Mills in 1986 that his career was rescued by his own son Mark, who took over management duties and attempted something that seemed destined to fail: reviving a 1960s sex god into an artist of renewed relevance.
But he did it, and within two years Jones was back on Top of the Pops, chomping his way through Prince's Kiss as if it tasted like Peperami. Over the ensuing three decades, Mark Jones, now 55, would continually reinvent his father, getting him to record better songs, with better producers, and often doing high-profile collaborations with the likes of Manic Street Preachers, Hugh Laurie and Jack White.
"We have a very special relationship, me and Mark," he says. "I'm grateful he's done so much for my career, of course, but I'm also gratified as a parent that he is doing something that clearly makes him so happy. He's not just good at his job, you know. He loves it."
Jones is now set to release a new studio album, his 38th. A scenario in which, say, Mick Jagger's new work would be proclaimed among his very best would be an unlikely one, yet you could comfortably say this about Jones's Spirit in the Room: the man has rarely sounded better.
Like so much of his back-catalogue, it is essentially another covers album, but the songs – by artists such as Paul Simon, Richard Thompson and Odetta Gordon have a depth to match the voice, and if there is a unifying theme, it is their sense of reflection. Like Johnny Cash in his latter years, Jones is increasingly using songs to brood over an increasingly evident mortality. "All my friends have gone, and my hair is grey," he sings on the opening track, Leonard Cohen's "Tower of Song". "I ache in the places where I used to play."
"I wouldn't have been allowed to do this kind of music 30 years ago," he suggests, "because it wouldn't have been seen as commercial enough. But I love that I'm now able to make music that really reflects me, who I am."
Only one track on the album gave him pause, Tom Waits' "Bad as Me", which, in featuring lyrics about Mother Superior in a bra and Jesus working behind a bar, he feared was blasphemous. Jones, a committed Christian – those crucifixes that used to nestle in his chest hair were not merely for show – would never knowingly blaspheme. But he liked the song, and his producer encouraged him to have a go at it.
It needed, however, some kind of damage limitation, just in case. "And so I inserted a laugh in the middle of it," he says. "You know, to show I was only joking, like. Because, let's face it, it is a pretty cheeky bloody song, isn't it?"
His most recent album, 2010's gospel-influenced Praise & Blame, reached number two in the charts, and Jones is already eager, if not downright anxious, to learn whether Spirit in the Room can go one better. This speaks volumes about his ambition. But why? What does a man who has already sold 100 million albums have left to prove? Shouldn't he be off playing golf instead?
"Golf?" he booms, horrified. "I never bloody liked golf. No, no. I've no hobbies. Music is what I do. It's why I'm here. I wouldn't know what else to do, to be honest with you."
Which is why this late renaissance has been so welcome. It gets him out of the house, and away from the pool – sunbathing being his only guilty pleasure these days. "Don't get me wrong, I do like the pool, but there's still so much more to do, the way I see it."
Consequently, he is always open, in theory, to any offers of gainful employment. No, he insists, he was not invited to represent the UK at this year's Eurovision before they plumped for Engelbert Humperdinck, but when BBC TV executive Alan Yentob approached him to become one of the judges on X Factor facsimile The Voice, he jumped at the chance, and not only because Yentob was very complimentary: "He said that whenever I was on TV, ratings shot up," he beams.
Nevertheless, surely he had to think long and hard before accepting what could so easily have become a poisoned k chalice? "Absolutely," he agrees. "And I had to wonder whether I really wanted the fame and intrusion this kind of thing brings. I also wanted to know who my fellow coaches would be. That was really important. I wanted to know we could complement one another, you know, appropriately."
Every Saturday night, then, Jones can be found sitting alongside Jessie J, the Black Eyed Peas' Will.I.Am and the Script's Danny O'Donoghue in his fancy red chair, dispensing wisdom and shedding, as is mandatory for TV talent shows, the odd tear. What is it, I ask, that he feels he brings to the show?
He stutters before answering, and as he does so, a blush actually rises to his cheeks. "Well, the others appeal to the young and hip folk out there, while I'm the old... the old... well, you know, the old-timer, I suppose, the one with all the experience, experience that I can hopefully bring to bear."
He reveals that the producers wanted him to spend as much screen-time as he could boasting about all those he has sung with over the years – Elvis, Sinatra, Sammy Davis Jr – but he has so far proved resistant. Or so he seems to think. "That would be showing off," he says, "and I don't want people to think I'm showing off, you know?"
Last year, halfway through a tour, Jones was admitted to a hospital in Monaco suffering from severe dehydration. But, as his website later protested, "There were NO heart problems." He recovered quickly, and says he has since remained in rude health. His vices, these days, are few. He has even cut down on his drinking. "I do still like a drink – drinks – especially with food, but the problem is that I find wine fattening now." His eyes widen, like a scientist making a new discovery. "There are calories there, you see. I never had to worry about calories before. My metabolism took care of that. It doesn't so much any more, so I've had to cut back."
And if he is not taking his health for granted any more, he says, it is because he is becoming increasingly aware that time for him is running out.
"I'll be 72 next month [Jones' birthday is on 7 June], and so I suppose I'll be lucky if I have another 20 years left. Twenty years is nothing. The last 20 have gone by like that," he snaps his fingers, "and that's scary, it frightens me. You know, if I could have one wish granted, it would be for immortality. God has given me this most wonderful life, and the only thing I hate about the ageing process is that, one day, I'm not going to be able to live it any more."
Suddenly, he looks quite bereft. He leans forward on the sofa and, his voice dropping to a gravelly whisper, says: "Hank Williams once sang a song called 'I'll Never Get Out of This World Alive'. I never thought of it like that, but you know what? He's right. None of us will."
'Spirit in the Room' is out on 21 May on Island Records