It may be the most infamous example of masonry going under the hammer since the Berlin Wall - an auction selling Turnpike Lane's Banksy is due to end this evening.

Florida-based Fine Art Auctions Miami is due to sell Slave Labour (Bunting Boy) in an online sale of street art at 8pm.

The auction has attracted attention from around the world after the stencilled graffiti was removed, wall and all, from the Poundland supermarket in Whymark Avenue where it appeared last May.

The area's Liberal Democrat MP Lynne Featherstone and Labour-run Haringey Borough Council have joined residents calling for its return, despite the apparent intent of the piece - drawing attention to the supermarket's now severed links with child labour and satirising the build-up to the Queen's Diamond Jubilee and the Olympics.

Poundland has denied any involvement in the piece's removal, and the auctioneer Frederic Thut has insisted the sale is legal and defended the house against claims it was stolen.

He says the graffiti was painted on a piece of private property and it is up to the owners what they do with it.

Even the enigmatic Banksy may have joined the debate, with a new rat stencil holding a sign that reads simply 'Why?' quickly covered in protective perspex.

In the frequently asked questions section of his website, he quotes the painter Matisse when 'asked' about auction houses selling street art, saying: "I was very embarrassed when my canvases began to fetch high prices, I saw myself condemned to a future of painting nothing but masterpieces."