AKA The Twigg!
know the spray place in crawley. if you mention the car they should remember it well. its a rag effect marble. its a pain to do but you blow the undercoat on. then the grean and roll a rag accross to get the marble. then a few coats of laquer over the top. i would say looking at it from a point of view i think if your doing rust on the sides rear then your going to have to get the whole side resprayed to match in this way. give them a ring and i am sure they will sort you out. but its gonna be expensive.