When do you change your cambelt on a rover 220 diesel?

Depends on the year of the car. Rover quoted 72K miles on earlier models I've known them go longer than that but I would eer on an early change [36-48K tops) for peace of mind ( It will be mighty expensive if it breaks). Incidentaly the 2Ltr diesel has two belts, one at each end of the head. The front one drives the cam and the rear one drives the injection pump. The change interval, I belive, depends on whether the belt tensioners are manual or automatic, early engines have manual tensioners and a longer change interval than the later auto type.