A neighbour admired a 1970s painting on my wall called Evening on Mount Olympus Not any old neighbour. She was a painter, someone whose work has been exhibited at the Tate, and whose husband is a Royal Academician. Evening on Mount Olympus is a picture of unshakeable provenance. Its even signed by the artist. How do I know the signature is genuine lets face it, signatures are the easiest thing of all to forge? It says, by Jim Parton, form 12a, you see. I did it, when I was 11. It was probably one of my very last paintings before the world of art lost me forever to football and, later on, girls...