Ian,
Believe the first line of your comment possibly sums it up, after 1974 vast swathes of land were seized and realocated, I have been told umpteen times that there is little chance that, even when you buy land through the correct process, you will own it.
You have to feel for the Orams though, they bought in all good faith, I have no doubt, but equally did they do no research? Equally who have they bought from a reputable company or the ubiquitous waiter who knows . . . . .