The Yorkshire graffiti artist known universally as Moose has what he believes is a cast-iron defence against accusations of urban vandalism.
He has devised a brand of street art which not only livens up city streets, but removes grime in the process. His method is to take any dirty inner-city wall or pavement, place a template over it and scrub the concrete clean, revealing an image as sharp as any spray paint which fades with time.
The artist's labours have brought in contracts from companies as diverse as Microsoft, Channel 4 and the drinks giant Diageo, and created art in improbable places - from Edinburgh signposts to London's Blackwall Tunnel. But the graffiti has pitched him into a legal spat with municipal leaders in Leeds, where he is based.
Much to the indignation of the artist's corporate clients, Leeds City Council demanded the "clean-up" of a piece of graffiti promoting Diageo's Smirnoff vodka in one of the municipality's gloomiest underpasses.
Smirnoff considers the artist's work a perfect way to reach a teenage market and is keen to commission Moose again. It claims the police were happy with the work's legality.
The row is a source of puzzlement to Moose, 39, who occasionally goes by his real name Paul Curtis, and who can earn more than £600 a day.
"As soon as I've done one it creates a lot of buzz; a lot of people start talking about it," he said. "It means I can create... images in horrible, shitty tunnels, dirty walkways, anywhere."
The source of the trouble has been a rather unfathomable message in 3ftletters for Smirnoff's "Lyriquid perfection" campaign, condemned by Gerry Harper, a Leeds councillor, as "sheer vandalism". Moose counters that he should not be prosecuted "for cleaning the walls". But Leeds City Council insists his work is illegal because any advertiser needs a permit. The Crown Prosecution Service says he may have been in breach of last year's Anti-Social Behaviour Act.
Smirnoff has removed the offending work - not because of the legality of the threat but by "its own volition" it said.