Buying a house built on land which didn't belong to owner

[soozmac]

I have had an offer accepted on a house in Edinburgh, which was built on a plot of land bought from a neighbour. But it turns out that the person who built the house did not stick to the original plot which he bought, but used an extra 45 square foot of unused, unclaimed wasteland, which he did not legally own. This now means that our solicitors are having to get the land registry office (I think) involved, to see if the sale can go ahead. Has anyone ever heard of anything like this? What is the likely outcome? I am worrying myself stupid here. The plot was bought in 1979 and the house was built in 1990.

This is maybe a slightly odd question, but as I am having to wait 2 weeks for a reply from the official agency, I thought I'd ask if anyone else has had the same experience.