I’ve read about other situations like this recently in the Daily Mail. This immigration official got some swift action from the local police—the people in the other stories weren’t so lucky (or well-connected).
As someone else has posted, the laws in the UK seem to favor the squatters over the landowners.
Fixed that for you. If this was most anyone else, the squatters would still be there.
Squatting is illegal in Scotland and NI, and in Scotland at least is a very serious offence and a jailable offence.
It is not illegal (ie a criminal matter) in England and Wales, it is civil. There are changes afoot to make it illegal in Eng/Wales though.