Don't clean this lorry - it's art

Most artists regard dirt and pollution as their enemies, destroying pigments and corroding stone carvings.

But Ben Long draws his images into the muck on the backs of lorries, using his finger as a paintbrush and the trucks' shutter doors as his canvases.

'It's pretty exhausting. It's very physical work - you're always stretching and getting up and down to look at it,' the 23-year-old said.

His day starts at 5am when he heads to New Covent Garden, the wholesale flower market in London which he uses as a makeshift studio.

With a vegetable pallet propped against the back of the van to give him something to stand on, he starts the five-hour process of smudging a picture into the dirt.

'At first I had a lot of problems getting permission from the security guards. They'd ask me to leave when I was halfway through a drawing. But now the pictures are better known I even get people asking me to do them,' he said.

Lancashire-born Mr Long, who finished a degree in graphic art at Camberwell College of Art in South London last year, has completed at least 40 of the grime pieces.

'What's important is that, once these are done, the trucks are getting driven off all round Britain. It's like having a big travelling exhibition,' he said.

Mr Long admits to feeling a pang when he sees one of his works of art washed off.

'I don't want to get attached to them, because I hate the idea that an artwork can become so precious that it loses its meaning and ends up being just about money,' he added. 'But at the same time, it's not good to see someone just wash one of them off after a couple of days.'

His eye-catching work has not gone unnoticed. It has been nominated for the £10,000 Prospects drawing prize, awarded by pop artist Peter Blake.