Thanks. Bit far from Devon, I'm in South Cumbria. I'll need to get the garage to do it. I'm struggling with car repairs at the moment. I've been diagnosed with costochondritis after a car crash 2 years ago. It took me 6 weeks and several boxes of pain killers to replace the bearings in the front prop shaft.
I'll need to do some more investigating, not 100% sure its the diff. There was a screech like a slipping fan belt and smell of burning rubber last night. Still sounds to be from the rear end. After the screech there was a clunk and it stopped. Today when I tried to find the noise it wouldn't do it. The diff does need replacing at some point, as does the power steering pump, both have some play.