Hi nodge,
Thanks for your replies.
I've had some advice from a friend of a friend who used to be a rover mechanic. He says that more than likely one of the rings is broken or stuck, or the rings are carboned up.
He's recommended/suggested that I put some oil additive/conditioner in and then take it for a good old thrashing !!!!
However, i'm a little concerned cos he said this will cure it or kill it !!!!!!
I'm thinking of biting the bullet and getting a full gasket and seal kit and stripping the head down.
you mentioned breathers in an earlier post. The Haynes bible doesn't really show where they are and which ones to check. The only 2 I found were the ones from the cam cover to the air inlet set up.
I'll try the thrashing thing later and let you know if anything improves.
Once again thanks for you patients and help.