The actor/writer/creator of the outrageous (and funny) Rocky Horror Show is today dressed in chenille leggings, vintaged boots, frilly camisole and a women's cardy. But no single head lifts up from the broadsheet of choice, even when O'Brien's voice becomes delightfully ebullient.
"I'm having the shepherd's pie, darling, and a glass of red," says the 71 year-old, (he looks 10 years younger). "What will you have?"
Well, the shepherd's pie also, please. And an answer to the big question, if you would. Is it true that you came up with Rocky, now in its 40th year and a show that has made you squillions, out of anger? When skittled off the 1972 stage of Jesus Christ Superstar by a less than supportive producer, you vented your spleen via the creation of a shock horror musical?
"Not really, darling," he says, with a wide smile. "Yes, my playing Herod didn't go well. I only got one rehearsal and they put me on a Friday matinee and Stigwood (Robert) came in and it was like a gladiator being given the thumbs down. It was awful, but I didn't care."
There's a contradiction there? "Well, it wasn't the be-all. I had a baby boy to look after so I'd have found work. But I learned from the experience. I felt Andrew (Lloyd Webber) tried this soul riff but he should have used rock 'n'roll. And he is devoid of soul."
The notion of a rock n'roll musical was lodged in O'Brien's hairless head but was the impetus to create an outrageous show – which weaved in themes of transvestitism, bisexuality and infidelity– born of 'I'll show 'em' spite?
Well," he says after a pause, "the truth is I wasn't really all there at the time. I was a person who was transgender who was hiding so much of myself. The person out on the street was coping but someone else was inside my head whom I didn't want anyone to see. I didn't want to be ridiculed. So the Herod thing didn't over-worry me. What really worried me was 'Who am I?'"
O'Brien outed himself to a degree via his musical's characters; life's outsiders, freaks and aliens encased it in a camp gothic world, some wearing costumes which screamed raw sex. "Had I never been transgender, Frank never would have been Frank," he admits. "It was about enabling myself. I suppose I was putting myself over the parapet. And Rocky has been a great ride for me. Not just financially. It's allowed me to be me. I'm free."
Rocky Horror was pre-zeitgeist, it anticipated punk, set the debate for linear sexuality and ran initially for 2690 performances in London. Eighteen months after opening it was made into a film which has since grossed more than $360m worldwide.
Yet, O'Brien, who landed his first screen role in Carry On Cowboy, as a horse-riding stuntman, plays down his success. "I was lucky," he says. "I arrived in London when the side doors of theatre offered open castings. The working classes had arrived. And I wanted to be a song writer, to be in the theatre. Success was about being continually employed."
He adds: "Work, for me, is just make-believe. I never wanted to play an emotional person, for example. Or do Shakespeare. That's why I love children in the audience."
O'Brien's conversation is underlined with egalitarian themes; he cheerfully trashes Lord Prescott, Rebekah Brooks, Baroness Thatcher, Sir Ian Blair and a Beatle. But how does having made a few bob sit with his social philosophy? "Easily, because I never made a lot of money at any one time. If I'd made it overnight, from nothing to megabucks, I'd have become a victim of excess. But it came slowly. Rocky initially meant I got a £16k mortgage on a £24k house."
Does he ever look to see what he's worth? "No, because I know what I'm worth. And what I'm worth is to be valued as a human being. I've got a house in London which I'm signing over to the children and I've got a house in New Zealand, where I'm going to live. In fact, I'm going to die there. You see, I've got food in the fridge and a roof over my head and I never forget that fact. I'm so grateful."
He speaks adoringly of his third wife, the 38 year-old German Sabrina Graf. "She was a fan, but I had to make sure she wasn't a bunny boiler. So we became lovers and I can't believe I have had the honour of intimacy with this beautiful creature."
O'Brien is the cat who has got the cream. Except in one respect. He didn't get to play Fagin in the West End. Producer Cameron Mackintosh caused offence by offering him a "bit part" in Oliver!, a show he 'would have done for nothing'. "No thank you! I'm a marquee name, darling."
He is. And so he played the role in NZ last year and picked up rave reviews. And if he got the call from Cameron now to play the West End? "**** him," he says, laughing so loud one or two Grouchos actually look up. "It's too late. I'm off!"
The Rocky Horror Show 40th Anniversary Tour, the Kings Theatre Glasgow, Monday to March 2 and the Edinburgh Playhouse, March 11-16.