So that's it really!
We're nearly at point of exchanging on our sale and related purchase and had the news ( from our buyers solicitor) that somehow we don't legally own our garden, never have! It should have been picked up by our conveyancing solicitor 5 years ago but it wasn't. They are denying all responsibility and say it is our fault for not telling them 
So now we have a house we cannot sell, unless our neighbour agrees to ' 'sell' us the land even though they have no idea they legally own it and it has never been 'theirs' in terms of usage.
So, be warned!!