I just remembered another way to do this.
Go along to your local Rover dealer and take proof of ownership and proof of your identity with you. Provided that it's the original radio in the car, i.e. factory-fitted, they should be able to give you the code for it there and then.
Some dealers don't charge for this service, although that really depends on the dealer. Best thing to do is to ask, obviously.
By the way, if you don't have the manual for the radio either, they really should be able to give you advice on entering the code as well.
Regards.
R Glass, June 2004