Lord Lloyd Webber has his shirt open to below his chest under a sleek, tight-fitting leather jacket and is on cracking, mischievous form.

We’re talking about Jessie J, who I think would make a rather good Mary Magdalene in the Lord’s new rock show, a reprise of Jesus Christ Superstar. (Mel C was offered and accepted the role.) He says that he and Jessie J are in talks about something else. Could she be making a guest appearance in Superstar, the new ITV1 series, which will deliver him his lead for the concerts on a UK arena tour? Or, perhaps, he wants her for Christine Keeler in his next project about the doomed figure from the Profumo scandal, Stephen Ward? Annoyingly, he’s keeping shtoom but he does tell me that Jessie J’s first singing appearance was his production of Whistle Down the Wind, when she was 11.

The singer’s most recent gig has been on BBC1’s The Voice UK. So what did her first employer think of that? “I don’t know what the problem was there,” Lloyd Webber says. “Everyone was out of tune all the time. I just couldn’t watch it. Unfortunately, I have perfect pitch – it’s either one of the great advantages or the greatest affliction in life. When people sing out of tune, I just can’t listen.”

We talk about his recent contribution to the Queen’s Diamond Jubilee concert, with him playing the piano to the song he created, Sing, with Gary Barlow. He looked pretty jubilant himself as the song reached its powerful finale, with the massed choirs of military wives and African children. “Yeah, well, we couldn’t have asked for a better result – we were at number one, by a long chalk, and I’m pleased about that because I think we got it right for the occasion, you know.”

The Lord now knows the Queen’s favourite tunes which include People Will Say We’re in Love and, rather fabulously, Miss Otis Regrets. These were sung on the Queen’s actual birthday, which she celebrated at the Lloyd Webbers : “She came round to my house and we did the cake there and a small cabaret that ended with us performing Sing twice for her, and she loved it. I was tipped off by someone who’s quite close to her what some of her favourite songs are, so we put them in the cabaret.”

“We had Gareth [Malone] there, and half a dozen Military Wives and a few friends from racing [Madeleine Gurdon, his third wife, is a keen horse-rider and former equestrian competitor], so we got their wives and we had the Racing Wives along with the Military Wives. It was a great evening.”

Before we move on to Superstar, I want to ask him about our recent debacle at the Eurovision Song Concert, being represented, bizarrely, surely, by Engelbert Humperdinck and coming almost last (this, of course, not for the first time). In 2009, Lloyd Webber was the man behind our entry; the singer, Jade Ewen, was picked by him having performed in another ALW television competition series, Your Country Needs You. The host country was Russia and Jade came fifth, the best result in seven years, singing a song co-written by Lloyd Webber.

“I don't think there’s any point beating around the bush [oh goodie; more plain speaking]. I’ll put it to you by asking you a question. Did you see the Eurovision Song Contest this year? [Er, no, only the aftermath.] Well, if you had seen it, you might have noticed one thing – I don’t think there was one black face on the programme.

“At the press conference in Moscow, I was asked, ‘Why have you brought a black artist?’ [Ewen is a beautiful, young black woman.] I said, ‘Because she is the most talented artist that we had and I think she’s a major, major star.' I think we would have come second but there’s a problem when you go further east...”

So you’re saying that racism is the reason why we didn’t win? “Well, it doesn’t mean that we would necessarily have won that year but we could have come second. If you’re talking about Western Europe – Germany, fine; France, fine; Spain, fine; Greece, fine; Scandinavian countries, fine. But Ukraine? Not so good.”

He was thrilled to get an interview with Putin: “The fact that I managed to get the only interview with Putin on the back of the Eurovision Song Contest meant the BBC’s Moscow political bureau was furious! They were absolutely spitting blood!” The Lord is clearly enjoying the memory of his moment as the BBC’s political correspondent.

So did he ask him any killer questions? “I said at the end, ‘Well, we’ve talked a lot about music – are there any circumstances, Prime Minister, in which you might become President of Russia again?’ He’d been doing that brilliant politician’s trick of using his interpreter when, actually, he understands English perfectly. So he dropped his guard and answered me in English...”

What was his answer? “Well, he started to talk and suddenly the interpreter came in – it was a bit scary but also really interesting. I think my favourite moment was when I got him to say that he’d put Russia’s vote behind us in the Eurovision Song Contest and the other one was when he said that his children were musical and I said, ‘Well, then, they’re the ideal act for Russia in the next Eurovision.’ And he did laugh.”

We move on to his latest project, Superstar. He wants to give me a potted history of Jesus Christ Superstar, which started life as an album in 1970, with Tim Rice as the lyricist and ALW as the composer (the role of Jesus was sung by Ian Gillan, then lead singer of Deep Purple). In America – where it was huge – the songs were performed as rock shows. Not so in the UK, where it was very much a rock opera in a theatre. The title song and Mary Magdalene’s I Don't Know How to Love Him were big hit singles.

The Lord says that there was never any idea, initially, of the record being done as a stage show, “primarily because Tim Rice and I would never at that time have thought anybody would be remotely interested in putting it on, particularly with that subject.”

“It got quite nice reviews but no reaction so Tim and I thought, ‘Well, that’s the end of Jesus Christ Superstar and nobody’s going to hear of it again.’” But then they got a call to fly to America, where they were shown full-page reviews in Life and Time magazines and were told, “Here’s your chart position – you’re at 21 with the album and for a double album that’s totally unprecedented, and we think you’ll be number one next week.” And within a couple of weeks, “it was probably the biggest thing in America since the Beatles.”

The Lord is very much of the opinion that, despite the success of the theatre show in London in the 70s, the songs work best when performed as a rock concert, which never happened in the UK and that’s why he’s so excited that it will finally be seen in this country going back to its rock roots in an arena setting.

 Comedian/musician Tim Minchin (who co-wrote Matilda: the Musical), apparently a Superstar fan from way back, has been cast in the pivotal role of Judas, while Radio 1’s Chris Moyles is playing Herod.

The idea behind Superstar, the ITV1 primetime show, which like ALW’s previous five TV shows on the BBC (from How Do You Solve a Problem like Maria? to Over the Rainbow) is to get the public to help decide who will play the leading role, alongside a panel of live show judges led by Lloyd Webber. Amanda Holden is presenting and confirmed judges include Jason Donovan and Dawn French – “She’s everybody’s favourite vicar so I thought we’d better just ask.” ALW says that we might well see Gary Barlow come on board, too.

“What I really, really want to do is to sit down with everyone and say, ‘There are certain reality-show clichés and I think we ought to have a gong system.’ It’ll gong us out if anyone says, ‘You’ve had a fantastic journey’ or ‘Although you’ve lost, I’m sure we’re going to hear from you again,’” he laughs.

It’s unfortunate for the feel-good factor that Tim Rice has made some much-reported disobliging remarks about the TV show, calling it “tasteless” and “tacky” and threatening to veto the winning contestant. Oh dear.

Naturally, this is fascinating stuff since both men own the rights to the show. But this is one subject where the Lord can exercise discretion: “I’ve said that I will not comment on what Tim Rice has said and the only comment I will make is that we have six girls starring in the West End right now [from the TV shows]... all kids who have actually, genuinely, got big careers now on the back of the BBC.”

Have you talked since he made those comments? “Well, we’ve been on stage twice together since then.” So have you made up? “I’m not even going there.” But he has to agree to what you do with the show? “Yes, and he has.” Otherwise you couldn’t carry on? "Exactly."

Rice has stated that he thinks the two are unlikely to work together again, saying, “You’ve got to have a young element... we’re not relevant as a team any more.” To which ALW retorts: “Well, strangely enough, he put in the Ivor Novello Awards programme, ‘Never say never, love Tim’ so...”

As for his other marriage (both men have referred to themselves as a couple apropos of their working relationship), he cannot speak too highly of his actual wife: “I don’t mind being alone when I’m writing or working but I do like to be able to touch base and she (Madeleine) has been an extraordinary rock for me. She’s a very strong character. It’s been 21 years and one of the nicest things is that she regards my first Sarah (Hugill as opposed to the second Sarah, Brightman), the mother of my two oldest children as more than a family friend who spends Christmasses with us.

“Madeleine’s very good at being inclusive and I think anybody who meets her feels that she’s friendly but I’m afraid that she’s also bright and doesn’t have a lot of time for people who she thinks are either trying to pull one over me or are sort of – shall we put it diplomatically? – not really pulling their weight. She’s on the board of my company now and she’s certainly more au fait with the music and theatre business than I am, say, with horses!”

He’s feeling very chipper health-wise, having lost two stone – “Everyone’s slim now. Dawn’s slim now and Katherine Jenkins... I didn’t even recognise her when I saw her running in the park last week.”

We last met in 2010 on the eve of the opening of Love Never Dies, the sequel to The Phantom of the Opera, soon after his prostate gland had been removed having been diagnosed with cancer. When I asked him, then, whether he was fine, he was a tentative: “Yah-ish. I’m going to have to keep my eye on it – be a bit careful. But it hasn’t migrated so far.”

He’d been told to look after himself and not do too much so, of course, he ignored the doctors and carried on. “Then I got a complication and an infection so I was obviously not on top form as a producer,” he says, at this interview, “and I think it’s not a great idea for a composer to also be producer of their own shows.”

At any rate, he has been given the all-clear in relation to his health now – “I mean, they actually told me not to bother coming back.” And Love Never Dies has also had a new lease of life, after opening, closing, reopening and closing again in London in a year. But now it’s going to Broadway and then China and as for the Lord, he says, “It’s time to move on.”

His mind is already focusing on the project after Jesus Christ Supestar. He’s fascinated by Stephen Ward, “probably London’s most popular, urbane, connected man ending up in the Chamber of Horrors in Madame Tussauds. And yet, there’s not one person I’ve met who was connected with anything to do with it, who hasn’t said to me that he was the most astonishing person. In my opinion, it’s a tale for today because it’s actually about the need for a scapegoat.”

 And what scapegoat is he thinking of in society today, I wonder? “It’s who comes out of the Leveson Inquiry, isn’t it? I mean, there will be a scapegoat for journalists who’ve done exactly the same sort of thing.” Hmm, you wouldn’t be thinking that the scapegoat is somebody with red hair, are you? And, the man who, after all, knows a thing or two about Rossetti, Burne-Jones and Holman Hunt, owning a fair few of them, quips – quick as a flash – “We’re not talking about the Pre-Raphaelites now!”

The first episode of Superstar airs tonight at 7:25pm on ITV1