There are several photos and two hyper-realistic sculptures. In one, the artist is standing in a corner of the gallery dressed as a tramp. His feet are wrapped in newspaper held together with parcel tape. His filthy old trousers are held up by a piece of knotted string. I walk around him, taking in the unhealthy skin, the rough beard, the eyes - one closed, the other half-shut with the pupil gazing into space. He's wasted and ill. His right hand is raised slightly from his side, fingers half-pointing, perhaps in a clumsy attempt to signal something. He doesn't have the muscle control or the mental focus to complete the gesture.
In the other sculpture, Gavin Turk - spruced up and almost unrecognisable from the tramp - has placed himself in someone else's art. He's in the middle of a magnificent, pillared vitrine, mimicking the pose - lying naked in a bath, his fine-featured head swathed in white cloth - of a martyr of the French revolution. The original painting was called The Death of Marat, and so is this. Non-period details include the lino- tiled floor and the modern, enamelled bath. The position of the right hand echoes the tramp's. I walk back and forth between the two figures, enjoying the sordid and the sumptuous, the neo-classical and the bang up-to-date.
The press release mentions that Gavin Turk turned up at the private view of the "Sensation" exhibition dressed as the tramp. The larger-than- life-sized triptych of photos mounted on the wall shows how he must have looked. But they were taken against a white backdrop, and so miss out the Royal Academy interior and the reactions of fellow guests. I wander over for a final look at the three-dimensional tableau.
A dishevelled bloke has just mounted the upper deck of the 185 bus and lurched towards a seat. Evidently he knows a woman passenger. He must, because he informs her that he's going to be dead soon.
She says nothing, so he informs her - informs the whole bus - that he's got a brain tumour. There is a lump on his skull, he elaborates. And he would like his acquaintance to feel the bump. She doesn't want to feel. But he does want her to, and moves in her direction. She's adamant that she doesn't want to feel his lump, his tumour or whatever it is, a note of panic in her previously well-modulated voice as she declares she's got a headache and just wants to be left alone. She's assertive enough - just - to make him back off and return to his seat.
"GOD IS OUR SAVIOUR," he says loudly. "GOD IS OUR SAVIOUR," he repeats. He says something about Jesus dying for us. "Would you give up your child for other people's souls?" he asks a young woman opposite him, over and over again (irony? craftsmanship? restraint?). He turns to the man in a suit sitting nearest to him, who's not having much fun. "If we haven't got God, what have we got?" No, not much fun at all. Now I dare say that what the demonic one needs is a bit of love and attention. But I get the distinct impression that every person in the bus is about a hundred miles away from providing those precious gifts.
Angrily he lurches to his feet. "Brain dead," he sneers at us. "You're all brain dead." He goes downstairs, "You're all brain dead!" we hear again. It's not clear whether he means the people on the lower deck - or if he's still talking to us.
He's out on the pavement. I hear one passenger taking a deep breath, another laughing, and several babbling inanely. I feel exhilarated too, but at the same time it's as if something has suddenly gone out of my life. I raise my right hand, focus my thoughts, and announce, "ART IS OUR SAVIOUR." Suddenly, silence. An array of egg skulls comes to mind, some shattered by the artist's signature.
Gavin Turk, 'The Stuff Show': South London Gallery, SE5 (0171 703 6120), to 18 October.
'Personal Delivery', Duncan McLaren's book on contemporary art, is out now from Quartet (pounds 12).Reuse content