If these people have been there for decades then they have rights by any law
In the UK if you occupy someones property as a squatter for 12 years and the owner does nothing about it legally then...................
Adverse possession can squatters take ownership of a property?
Adverse possession is the term used to describe the process by which a squatter, who isnt the legal owner of a property, can take ownership of the property by virtue of having lived in it for a certain period of time. It is commonly known as squatters rights.
The amount of time for which a squatter needs to live in a property before they can apply to be registered as proprietor of the land depends on whether the land is registered or unregistered. For unregistered land, a squatter can claim ownership after a period of 12 years adverse possession of it.
For registered land, a squatter in occupation for 10 years can apply to be registered owner of the land.
The application can be made if the squatter is still in possession, or has been evicted within the previous six months by the registered proprietor. Notice of the squatters application will be given to the registered proprietor, who can object to the application within a specified time limit. A squatter will be registered if one of three particular conditions are met.
If the squatter is not entitled to be registered, the registered owner then has two years to obtain possession against the squatter. If he does not do so, and the squatter remains in possession, the squatter can apply once again for registration as owner.
Rest is here