THE initial signs are that the Marti Pellow interview will be as crackly as an old, sleeveless album. Despite a relationship that goes back to the beginning of time (well, 25 years) a sinking feeling develops when we meet in a quiet corner upstairs at the SECC in Glasgow.

Pantomime producer Michael Harrison of Qdos Productions is riding shotgun during the interview. “What’s up, Marti?" I ask the singer and actor. "You’re a big boy. Surely you don’t need Michael here to hold your hand?”

Pellow looks at Harrison, Harrison looks at me with eyebrows raised and then back at the star of his latest panto, as if to say: "Can I leave you to it?"

The Wet Wet Wet frontman, however, is still unsure. It seems the pair have cut a deal to make sure he’s not left unattended. It makes me wonder why Pellow is so guarded. Have his years in the business left him suffering from Headline Fear? Come on Marti, it’s nearly 20 years since the drug revelations, the band split, the name calling. Yes, we had our differences when I wrote the band’s biography and you weren’t too chuffed about some of the content. We’ve since kissed and made up. We’re 50 million records on. And you’ve built a nice career in musical theatre, starring in everything from Evita (playing Che Guevara) to Chicago (wicked gangland lawyer Billy Flynn). And you’ve got your own solo music career, which is going gangbusters. Love is all around, Marti. So sit down and blether, for God’s sake.

Thankfully, the Geordie theatre producer slips off to one side (artistes are all too often guarded when guarded) and if Pellow is simply resigned to the one on one it doesn’t show. In fact, he’s back to being the upbeat Pellow, speaking animatedly and sitting on the edge of his seat, the opposite of the reluctant interviewee.

We talk about his return to Glasgow to star in the panto Aladdin at the Clyde Auditorium. Pellow, who is 51, played the Abanazar role in Birmingham last year to great success. The Hippodrome achieved its highest ever panto sales and his critics were impressed. ("Marti Pellow makes for a fantastic, boo-able pantomime villain.") Yet there was a time when only pop stars of yesteryear turned to panto, and indeed musical theatre. Pellow has used the word "credibility" like a mantra in past conversations. Did he feel this was a pointy-toed slipper in the wrong direction?

“Naw,” he says, laughing. “I was doing Willy Russell’s Blood Brothers last year when Michael came to see me and asked me to do panto. I said I didn’t know if it was for me and I was hesitant but it wasn’t a snobby thing. It was about standards and I don’t want them to drop. But I know Qdos productions are pretty awesome so I said, ‘If I can get to do the music, write for the characters [come up with the songs to provide the narrative for the story] ...' And when he said yes I was in.”

Did he fear the comedy element? “No, because Abanazar is straight. It’s easy to be seduced by laughter but for me the comedy lies in me not acknowledging the comedy and moving some of the story on through song.”

Nor did he fear the acting. Pellow makes the point he has played baddies before, such as Billy Flynn and the dark Daryll van Horn in The Witches of Eastwick. “I’ve always loved panto. I’d go with the Boys Brigade every year to see Stanley Baxter or whoever at the King’s. I’m happier playing an Abanazar than an Aladdin.”

During the Wets' success Pellow was offered films, major acting gigs. He always turned them down. What’s changed? “I wasn’t ready. Not because of the pop star thing, but more to do with confidence. I was being asked to come out of my comfort zone. And did I want to play in a show for six to eight months when I could appear before the same amount of people with the band in three nights, and miss out playing in Sydney or New York? No, I had to grow into the theatre thing.”

In the early 1990s Pete Townshend of the Who begged Pellow to do Tommy. “I said no but it was thanks to appearing at the Royal Albert Hall for Pete and Roger [Daltrey] at the Teenage Cancer Trust gig [in 2001] that I landed Chicago. I was singing with Ruthie Henshall and there were a couple of producers who saw me and said, ‘We want you to be Billy Flynn.'”

The fear was still in him. And the unwillingness to commit. But Pellow was won over. “I learned the challenge of theatre is to avoid it being Groundhog Day, or you can go stir crazy. Now I realise you get to see cities, to really enjoy places you never had before.”

The singer speaks at 78rpm. He’s smiling, as always, but half an hour in he is still on the front edge of the seat, never relaxing into it. It’s as if he has to be on his game. But that’s always been his way. Pellow comes alive on stage and he can work a room like no other. But offstage he lacks confidence. His drug problem, which began in 1996, was partly a result of never being quite sure of who he’s supposed to be or his place in the world.

But then Pellow’s journey has been incredible. He was selected by his Clydebank schoolmates to form a band because he looked right and was cheeky. Then they realised he could sing more than the pants off a song. But he wasn’t the confident boy the band members thought he was.

“When I get nervous I smile,” he says. Was there always an insecurity? Was this why he would often shy away from interviews, even having drummer Tommy Cunningham pretend to be him for American radio? He opens up. “Oh, come on. I’m a singer-songwriter. I’m a writer. All writers have that built-in insecurity. Of course they do. And you know, no matter if I were in my twenties or in my fifties there’s nothing I like better at two or three in the morning than going over to the s***box [his personal metaphor for self-doubt] and pulling all that stuff out of my head.”

Did he feel undeserving of the fame and success that came his way? Pellow thinks for a moment. “No, I didn’t. Here’s what it was. When we were going on a journey, to land a record deal or get Top of the Pops or whatever, that was fine. When you’re a teenager it’s a room you want to be in. But then you get in the room and it’s not as comfortable as you thought it might be. The chairs aren’t as soft, the lighting isn’t right.”

Did he feel it was better to travel than to arrive? “Absolutely. That’s it. And once I had arrived I found the goalposts were always being moved [in terms of expectations]. For example, we used to have a chart system, with a top 10. God, no pressure! You worry how the record will be perceived by your peers. Then you worry about what to do when you’re not in the charts. You start to ask questions. ‘What is it you like about me? What do you want from me?’ Things like that can live inside your head very easily. But when it’s all about youthful enthusiasm it’s very, very different.”

Did Marti Pellow want to go back to being Mark McLachlan? “Mmm,” he mumbles, tossing the question around in his head, perhaps not sure which way up the answer will land. “No,” he says, eventually. “Be careful what you wish for. You see, fame is a love-hate relationship, especially with writers. One day you think, ‘This is the best thing I’ve other done,’ and a week later you’re saying, ‘This is a pile of s****.’ But I couldn’t give up those incredible highs, even when they come with the incredible lows.”

It’s perhaps not surprising heroin provided an answer for a while. Pellow worried about his contribution to Wet Wet Wet’s songs. He worried about being perceived as being uncool, how he craved the kudos of a band such as Steely Dan. He was never content. Always looking around. Never quite of any one plan, any one place. One minute he’d buy a mansion in Helensburgh, the next he was off to New York.

“That’s the thing about fame. Once the gates open you’re holding on for dear life, and then at times you think: ‘Helensburgh. Ice-cream.’”

He’s never been the complete pop star, that’s for sure. Which is why the former apprentice painter and decorator slept in the servants' quarters and painted his Helensburgh home himself. “I still do that sort of stuff,” he says, grinning. “There were boys doing a job for me recently and I was at the window, and I wasn’t sure if they were doing it right so I got in amongst it. That’s because my family were in the building trade. I love working out what makes things work. I love doing practical puzzle solving.”

The family was a central pillar of his life but following the deaths of his mother Margaret, father John and brother John Pellow now has no immediate family. “Yes, but I remember all the good stuff. I was super close to my mum, and my father, and we really grew into each other. But they are still with me. I still wear them. I can smell something and I remember them, and I flash back to journeys with them. I really miss the words 'mum’ and ‘dad’. I miss the chance to say those words out loud. So I do it. I speak to them sometimes. I need to. Why not?”

Does he go back to Clydebank? “Yeah, I came up early this week and went over because the ABC cinema is being pulled down. I wanted to see its innards. It’s Art Deco, which I love. I needed to see the heart of it. I watched The Three Stooges and Flash Gordon there and later I watched A Star Is Born with Barbra Streisand. I spent so much time there. It was great escapism and I loved seeing this starry world.”

The Wets developed in their council house kitchens, playing local gigs, but if he were a teenager now would he have had the confidence to apply for The X Factor?

“I think I would have gone through Facebook or YouTube. I’d have been singing in the bedroom. There’s a place for X Factor, but not for me or Wet Wet Wet.”

Who knows what would have happened had he not been encouraged into the Wets. What’s undeniable is that Pellow loves songs. He’ll talk at LP length about his favourites. We chat about his covers such as Maggie May. “Rod screamed it. I whispered it. I love taking a song and breaking it down. I did the Love to Love album for that reason. Just like my dad loved taking things to bits, I love working out how a song works. That’s why I took Chris Cross’s Sailing, which is hypnotic, it tumbles. And I analysed it. Now when I write I can understand how to build a song. I love bringing a pop sensibility into musical theatre. It’s a lovely hybrid and it’s absorbing for me.”

He didn’t analyse Love Is All Around enough, at one time refusing to record it, I remind him, hoping he’ll laugh off his folly (It was No1 for 16 weeks and secured each of the Wets a £1m advance on their next album). And he does. “I’ve had enough time to look back at it objectively,” he says, laughing. “And people love it. It’s not bloody Agadoo. It’s not Ob-La-Di, Ob-La-Da. It’s a good song.”

Pellow may still have some of the insecurities of early years, but he’s also grown up. Once, life was about Ferraris and mansions and having curries flown across to the States, but reality has dawned.

“Touring in musical theatre has opened my eyes,” he admits. “You go to places like Rotherham or Hull for a week, out of the London bubble, and you realise a lot of communities are struggling.”

The man who grew up a council house appreciates Scotland is struggling. “I look at the shipyards, I look at our history. But do I want nationalism? I really don’t know. I just want what’s best for my country. I love Scotland. I carry it with me. But I’m not knowledgeable enough to peel back the layers of what they [politicians] tell me. Yet I was scared to realise when I came back from America we were out of Europe. Wow!”

Pellow lives between leafy Berkshire and the States. “I take long leases in homes in America. I had a loft in Los Angeles recently and moved into an arts commune. There was a wee pool area and it was great because no-one knew me. I just said I was a songwriter.”

And when he played them a few songs? “It was, ‘Ah, you’ve done that before!’ The songs I played them I had written with the Tower of Power horns and Quincy Jones boys, guys who wrote Boogie Wonderland. The album comes out in February.”

Did Donald Trump surprise him by winning the American presidential election? “Oh, aye. I thought the lady [Hillary Clinton] was the better choice but in a global sense we're all frustrated and looking for answers. And it’s not good because we’re looking for answers in the wrong place.”

What about Pellow's personal life? Is (former model) Eileen Catterson still part of it?

“I love her to bits, and she’s so supportive of the projects I work on,” he says. Will he marry her? “We are happy,” he says, smiling. “If we get married you’ll be the first to know.”

Pellow laughs a great deal during the chat. But is he relaxed? Not if his seat position is anything to go by. And the number of times he invokes the word "songwriter" as his profession suggests he’s trying too hard to convince. He still needs validation. He still doesn’t quite fit it. So you feel for him, that someone with so much talent doesn’t always wear his own clothes comfortably.

Yet, he’ll wear the Abanazar silk suit well. And he’ll love the panto applause. Pellow certainly maintains he’s happier these days.

“You have all these insecurities as a writer when you’re in your twenties, but now you can look back and say, ‘You know, this ain’t bad.’”

He adds: “Here’s the thing. I always had dreams of being on Top of the Pops, after seeing Sweet singing Blockbuster. I loved the sparkle. And I’ve done that. And to have a career that’s run so long, and all the good and the bad that’s come with being in a band ... well, I can’t complain at all, can I?”

Aladdin is at the Clyde Auditorium, Glasgow, December 10-31.