The 13-year-old burglar Freud asked to pose

The 13-year-old boy, Charlie, lived near the artist in Delamere Terrace by the canal in Paddington in the Forties - then a tough area, although nearby Little Venice is highly fashionable today.

Charlie broke into Freud's flat towards the end of the war in 1945. The artist - grandson of Sigmund Freud, the father of psychoanalysis - apprehended him, but instead of calling police asked the boy if he would sit for a portrait.

He agreed and Freud, then 23, dressed him in a military jacket bought from a rag-and-bone man under a nearby canal bridge.

Boy In A Red And Blue Jacket, drawn in pencil, coloured chalks and pastel on brown paper, which depicts Charlie as a sharp, streetwise youth, will be shown at Stephen Ongpin Fine Art in Mason's Yard, St James's, as part of its Master Drawings London selling exhibition from Saturday for six days. The portrait is now worth £450,000.

Charlie and his brother Billy subsequently appeared in several works by Freud during the late Forties and early Fifties. An older Charlie appears in the painting Smoking, formerly in the collection of Simon Sainsbury and recently bequeathed to Tate Britain.

Today the world record price for a Freud stands at $33.6 million (£17.2 million), paid at Christie's in New York in May for his image of London benefits supervisor Sue Tilley asleep. This week his Naked Portrait With Reflection went for £1.8 million at Christie's in London. Another great 20th-century British artist, Francis Bacon, caught George Dyer burgling his flat in 1964. He, too, did not call the police and the pair became lovers, with Bacon painting him on a number of occasions.