because it's the only painting by pietro lorenzetti in the uk.is work still exists in its originalform, this is a fragment of a much larger altarpiece, but when they bought it here for more than £5 million in 2012 it's set a world record for the artist. but time had not been kind to this tiny work of art, buried under varnish, dirt and clumsy repairs. so in 2013, the painting was sent to the national gallery in london to be worked on by one of the world's best restoration teams. repairs were done a long time ago using gold—coloured bronze, powder, as paint, and that had discoloured enormously into a kind of slimy green and black. smears across much of the background. st peter was quite buried under layers of varnish. the fact that paul is wearing these kind of wonderful lilac and mustard robes. when he arrived, he was looking like a franciscan monk — he looked very brown—grey. you might be thinking pietro who? he is not grow well known in this country, but one of the biggest developments in the history of art might never have happened without him