Recently I read this piece in the Daily Mail, about the sale of Banksy’s Kissing Coppers 2004, one of Brighton’s best-loved landmarks, at a Contemporary Art sale in Miami. I remember it well. It was painted on the wall of the Prince Albert near where I lived in the North Laine. Just looking at the photo I can feel the time and place again, a hazy summer evening walking home from the train station with the bell-ringers practising at St Peter’s, and the sound of sea shanties from behind the Victorian etched pub windows of the Pond Tavern.

I haven’t been that way in a long time. I didn’t know that the painting had been spray-painted over by vandals, and subsequently restored, or that it had been removed and replaced with a copy. Now it has been sold in America for $575,000. The Mail implies that the painting as sold, with the head of the left-hand copper restored by Jez the Barman, is effectively unoriginal, and that the buyer has been conned. The debate about whether a work has been over-restored must be as old as painting itself. This is Banksy’s true entree into the art historical canon. We are asking of Kissing Coppers exactly the same question we ask of Michelangelo’s Sistine Chapel Ceiling or Leonardo’s Last Supper: Is what we are seeing exactly what the artist painted? Fortunately with the Banksy we have an image taken after the vandals’ spray-paint was scrubbed off and before Jez got to work. As you can see, the damage isn’t excessive – the painting is hardly ‘obliterated’ – and this is a thoroughly acceptable degree of loss and restoration for a fragile piece in an exposed position. Any quattrocento fresco as you now see it will have had similar treatment.

‘Kissing Coppers’ was one of Banksy’s last works as an outsider, before he became part of the cultural mainstream in the mid-2000s. In 2007, he was named ITV’s ‘Greatest Living Briton’ in the art category. In May of that year his ‘Space Girl and Bird’ sold for £288,000 (Bonhams ‘Vision 21’ April 25th 2007 lot 299), and in Bonhams Contemporary Art sale that October, every piece of Banksy’s sold for double its bottom estimate. Ever since, Banksy has remained a headline-grabber in the contemporary art market. In June last year his mural ‘Slave Labour’ sold for $1.1 million at a secret auction in the basement of the London Film Museum. His autograph replicas, copies on canvas of his original work sprayed on public walls, sell as well as the originals, and he has begun a new line in defacing ‘old’ art, most notably ‘The Rude Lord’ (Sotheby’s Contemporary British Art September 12th 2007 lot 9) in which he painted a flipping-off middle finger onto a 1780s portrait by Thomas Beach. This sold for £320,900. Technically this is a sale record for Beach.

As a lover of painting I am glad that Britain’s often-voted favourite artist should be a painter, but defacing old paintings is wrong; it’s discourteous, and it’s derivative because it’s been done before, very recently by the Chapman Brothers. And graffiti belongs on a wall, as a nod and wink to passers-by, a joke for its friends, a part of the neighbourhood voice. On the side of a pub in Brighton ‘Kissing Coppers’ was a living work. Stripping it off the wall and selling it is like picking wildflowers and taking them home. As the red head said in the Brighton Argus this month, ‘when [Kissing Coppers] was free it was priceless.’