It is. It's just a civil offence, except for certain limited circumstances. In the broad it becomes a criminal rather than civil matter when there is an aggravating factor.There isn't a court case since trespass isn't an offence.
I'm in the process of suing the scaffolding contractor for the developer of an adjoining plot as their minions refused to remove themselves and their 7.5tonne truck from my yard (rated to 3tonne) when asked to do so and, on calling the boss, they didn't call their minions and shift 'em. My exact words were, after several minutes of "Why is this my problem?" "Well, they're working for you on your time and on your contract," were, "If your staff, materials and/or vehicle are still inside my boundary two minutes after this call ends you're getting sued."
They were still there two hours after the call ended.
The boss is still professing to not understand why they're being sued. I don't think I could have been clearer. With their costs, my costs and the property damage claim factored in they're looking at a bill of getting on for £25k at the moment. As I offered in writing to settle for what I'd spent on spanking them so far before serving the suit (around a grand) and they turned it down I suspect their insurers will either deny their claim or say, "Here's the grand you could have walked away from it for. Have a nice day."
A little bit of sex wee comes out every time I think about it as the plethora of photos, videos and eye-witness statements means they haven't a leg to stand on.