I can't find any evidence of it online now, but I do remember another prison near here having a very successful art facility in the 1980s, with the intention of rehabilitating offenders. This ran well for many years - until it was discovered that a lot of the paintings, which were done in the style of minor, but collectable, artists from the late 19th and early 20th centuries, were being given to visitors quite innocuously, but then sold through several galleries in London as genuine items.