From a lectern by the screen, Stewart informs us we can shout as much abuse as we feel we need to, and tells us not to be shy about going out midway through to get drinks. Then he introduces us to 'my mate, Ronnie Wood', who walks on wearing a nuclear orange shirt. And, as the lights go down, they both scuttle, giggling, to their seats in the front row. ('Me and Woody together,' Stewart will say later, 'are like schoolboys. I keep forgetting I'm 48. Once I get with him, it's all over, bless him.')
The programme is in the usual Unplugged style - an unobtrusive studio set, a small but noisy audience in the round. Stewart sits on a stool in front of his band with his sleeves rolled up and sings 'Hotlegs' and 'Tonight's the Night'. After a while, we see Ronnie Wood come out with a guitar and perch beside him like a roosting crow. They play 'Maggie May' and 'Reason to Believe'. When the audience at the concert applauds, the audience in the cinema claps too.
But at the screening, those close enough to the front get two shows for the price of one - the events on the screen and the events as interpreted by the pair of celebrities in the front row, the latter providing, as it were, subtitles for the hard of drinking. Up on the screen, Stewart introduces his version of the Tom Waits song, 'Tom Traubert's Blues': down in the front row, Ron Wood jerks himself almost clean out of his seat and shouts 'Tom Trousers Blues - ha- haaaarrggh'. Up on the screen, Stewart introduces Wood: down in the front row, Stewart springs up and shouts 'weeeurrrrrghh' in Wood's face. During 'Every Picture Tells a Story', they kick their legs up in the air and make unison cycling motions with their feet. And so on (with many variants on hissed laughter, many applications to the bottle at their feet and, for Ron Wood, one quick sprint to the bathroom) for an hour until the film ends and the lights come on and Stewart stands up at the front again and shouts, 'Right, let's all go and have a drink then.'
What with all the tabloid babble and the Hello] spreads and the wives with the mile-long legs who are young enough to be his offspring, it's sometimes hard to remember what Rod Stewart does best. And it would be fair to say that Stewart himself has thrown us off the scent occasionally, during his spandex trouser years particularly. Let's face it, at times the sheer naffness of Rod has obscured an essential fact about him - that he has one of the best voices that ever sang in a rock'n'roll band. Which is what makes this Unplugged album a particularly good idea. It's just Rod and a bunch of acoustic instruments and a set of mostly old favourites, sung with touching vigour and swagger. It reminds you how good he was and tells you how good he still is.
The day after the MTV screening, Rod Stewart visits his record company. This is not something that artists of Stewart's standing tend to do very often, and if they do, it is not normally to walk the humble corridors of marketing and publicity. But then Stewart is one of the few people on earth who can make a charismatic entry into an open-plan office. You hear him first from way off, emerging from the lift, shouting 'What a marvelous place]' in his favoured comedy voice - an impression of a posh, half-cut old buffer, with a spot of Frankie Howerd ('ooh, no, don't, don't]') and a little Leslie Phillips ('I say]'). He's wearing a deafening black and white check suit and his wrist is heavily garnished with silver jewellery. 'It's all right,' he shouts, as amazed people look up from their desks. 'I'm on the label.' He's shown into a sideroom ('I say] Delightful]'), and a bottle of chilled rose is produced. 'Nectar,' says Stewart. 'Are you allowed to drink on the job, old boy?'
When he's not messing about (ie, about 20 per cent of the time), his accent is cockney and has, like his singing voice, a continuous soft rasp to it as if perpetually on the edge of breaking. 'My voice is better now than it's ever been. The phrasing is better, it's a thicker, rounder voice now, and I've got a higher range. Well, you should get better, really, at your craft. I've been at it 20-odd years. I'd hate to be like Roger Daltry. He still sounds the same as when he started - can't sing to save his life.
'I look after my voice like a child. When I'm on tour, it's almost like I'm a prisoner of my own voice, locked in rooms, surrounded by humidifiers, unable to talk. But the one thing I can't stop doing is drinking. Because I do like a drink. I don't take any drugs, I don't smoke and never have, but I do like a drink, and that's the one thing that cuts your voice in half. I used to drink Bacardi and Coke and then go on stage and wonder why my voice didn't work.'
Later this year, Stewart will take the Unplugged show on tour in America. He says he'll sing songs by Dylan and Van Morrison. 'And it's going to give me a chance to be a wit, be a bit of a Max Miller. Because I've always fancied myself as Max Miller.
'Most of my songs work in this acoustic format, because most of them were written like that.' But not the camp disco-stomper, 'Do Ya Think I'm Sexy', surely? 'That's the only song of mine that pisses me off. I don't think that will see the light of day again. If it was a good song and I enjoyed singing it, I wouldn't care, but it bores the tears out of me. The trouble is, everyone thought I was singing about myself. But, if you listen, that song is in the third person.'
That bleary anthem 'Sailing' doesn't get on to the album, either, but not because Stewart finds it tiresome. ' 'Sailing' belongs to the British and it doesn't mean anything outside this country. You know, when I did 'Sailing', it was 10 in the morning. It was recorded in Muscle Shoals. And they said, 'Right, Rod, we'd like to do this right now, thank you.' And it's a dry state - you can't get anything to drink out there - and I was thinking, they're going to make me sing 'Sailing' at 10 in the morning without a drink?'
There is a moment on Unplugged where Stewart manages to move himself to tears. The song is the Van Morrison's 'Have I Told You Lately?' which Stewart sings with his eyes clamped shut. Then he makes a cradling motion with his arms and, next thing, the song has ended and he's furtively dabbing his eyes with a towel. 'It was genuine. I went all silly. Big old tear coming down me face. It was one line in there. Although the song is meant to be about the relationship, there was one line that reminded me of the baby. And I thought of my wife and everything and I just went into one. Usually it's only when Scotland score that I get tearful.'
Stewart says he modelled his voice on Sam Cooke's, Otis Redding's, Bobby Womack's. And he must have modelled it fairly accurately, because it's now thought fit to blend with Aretha Franklin's. They sang together recently - an occasion on which Franklin bared slightly more than her soul.
'I did this show called Duets, which may be shown in this country. It was Elton John, myself, Smokey Robinson, Gloria Estefan and Bonnie Raitt. And we did two songs each with Aretha. I shared a dressing room with Elton on that show, and Aretha had swiped all the coathangers before I got in there. Anyway, we did 'People Get Ready' and 'This Old Heart of Mine'. She's huge, you know. We were doing the encore and she was singing and getting carried away and this big old bosom came out right in front of me. It was only this tiny theatre, but she had to run off the stage and put it back in.'
But then Stewart himself has a reputation for flinging his body about on stage. Odd to see him confined to a stool for the Unplugged show, rather than hoisting the microphone stand around like a dangerous cheerleader. 'The microphone stand technique has probably been copied more than my voice has. I joined Long John Baldry's band in the mid-Sixties, and the first night we played was in Manchester and I got on in front of the mike, stood up straight and stiff and nervous - and I heard him bellow from the back of the hall, 'Young man] Roddy] Get your legs apart, dear]' That's how my moving around started. The mike stand thing really got into its stride with the Faces when the critics started writing about it. I threw it up once in Detroit and it got caught up in the lighting rig and didn't come down. What do you do? The band's playing on and I'm looking a right idiot.
'The Faces were a terrible band to record, you know. You couldn't get us out of the pub. It was terrible. As someone from the NME once said, being on tour with the Faces is like Christmas Eve every night. These days I can't tour in the summer because the pollen just messes the voice up. I can't compete with the rape - you know, those yellow fields? As long as they're around, I can't sing a note. But the Faces always used to do Christmas shows here, and I used to do them, too. Maybe that should be my little section of the year - the run up to Christmas.'
On his way out, Stewart poses for pictures on the landing, astounding still more passers-by. ('Just having a few photos taken, dear. I am on the label.') He says he has a ticket for the Cup Final replay and the last sight the office gets of him, he is heading into the lift with his manager, singing 'I'm on my way to Wembley / Me knees have gone all trembly'.
'Rod Stewart, Unplugged . . . and Seated' is released on Monday