This was true, of course; and yet not. There certainly were learned works on graffiti, chock full of sociological jargon: cultural disenfranchisement; urban alienation. But she flattered herself that she might find something amongst this litter of scrawlings that previous analysts had not: some unifying convention perhaps, that she could use as the lynch-pin of her thesis. Only a vigorous cataloguing and cross-referencing of the phrases and images before her would reveal such a correspondence; hence the importance of this photographic study. So many hands had worked here; so many minds left their mark, however casually: if she could find some pattern, some predominant motive, or motif, the thesis would be guaranteed some serious attention, and so, in turn, would she.

'What are you doing?' a voice from behind her asked.

She turned from her calculations to see a young woman with a pushchair on the pavement behind her. She looked weary, Helen thought, and pinched by the cold. The child in the pushchair was mewling, his grimy fingers clutching an orange lollipop and the wrapping from a chocolate bar. The bulk of the chocolate, and the remains of previous jujubes, was displayed down the front of his coat.

Helen offered a thin smile to the woman; she looked in need of it.

'I'm photographing the walls,' she said in answer to the initial enquiry, though surely this was perfectly apparent.

The woman - she could barely be twenty - Helen judged, said:

'You mean the filth?'

'The writing and the pictures,' Helen said. Then: 'Yes. The filth.'

'You from the Council?'

'No, the University.'

'It's bloody disgusting,' the woman said. 'The way they do that. It's not just kids, either.'

'No?'

'Grown men. Grown men, too. They don't give a damn. Do it in broad daylight. You see 'em... broad daylight.' She glanced down at the child, who was sharpening his lollipop on the ground. 'Kerry!' she snapped, but the boy took no notice. 'Are they going to wipe it off?' she asked Helen.