Timpsons will be able to cut you a replacement with their off the shelf blank - got one (two actually, as the locks were changed on this car at one stage) yesterday - about £9 a key (yes, saw me coming but I was in a rush).
Chappie asked 'has it got a transponder chip' (Timpson's records seem to suggest every Rover has a transponder chip in the key) - nope, it's a separate fob. No hassle. Sound bloke actually - let me wander off with one key and check it before paying.
Obviously not the bendy Rover type, but they'll do when the time comes...cos senile