[ensignavenger]

So in the UK if someone trespasses on your property, you can't call the cops to have them removed, you have to file a lawsuit?

[analog]

Well, before the squatting laws were changed, effectively yes. You had to go to court, get a court order, then if they ignored that then bailiffs and possibly police.

Edit: squatting was I believe a special case as squatters gained rights as residents. If you are asked to leave and don't, I believe the police could then be asked to remove you.