Round-up of advice posts from PP who have stated to have legal or sector experience, for OP’s use. Hope it helps:
Eloisedublin123
Surveyor here. They need to be prove they have been using the land for 12 years to make a claim. Or walking through it as a shortcut etc for 20 to claim the right to continue to do that.
AdaMcGrath
Hi, I’m a former property litigator (moved practice because I couldn’t take this kind of CFery any more!)
You need a property litigator to look at this. The timeframe you’re talking about means they can’t have acquired title to the land. The amount of time needed is a bit more complex than others have set out and it depends on whether the land is registered at HM Land Registry or not and whe; it was registered there.
The fence is their property come what may. The advice would usually be send a letter with copy evidence of your ownership and tell them they are to remove the fence within x days (say 14 but it depends on how much fence there actually is and you need to appear reasonable should it ever end up in front of a judge). If they don’t remove the fence you do it making sure you don’t damage it and then put it back on their land. I’d then erect your own fence to make it clear where the boundaries are.
You’ll also need the solicitor to check the trees subject to the TPO. It you might be able to get that information yourself if you phone the local authority and explain what’s happened. Lots of photographic evidence is always really helpful.
Finally your Solicitor’s letter will be making it clear that if you have to bring enforcement action that they will be liable for the costs of that.
Hope that’s helpful.
Annoyance
There's a lot of urban myths surrounding adverse possession. Way too many people seem to think that if you use some land or buildings for 12 years then you automatically receive a certificate in the post with a congratulatory letter and then you'll live happily ever after. It doesn't work like that. You have to go to court and prove everything and do a load of legal paperwork, and prove that you genuinely couldn't find out who owned the land. It's rare for that to happen with registered land because anyone can go online and do a Land Registry search. The owner of the land needs to be contacted and the thief has to prove that they genuinely couldn't get in touch. It does still happen sometimes but it's way more difficult than a lot of people seem to think.
itssadsometimes
Great advice here.(lawyer).
The only person who can screw this up is you if you try to be nice.
Solicitor tomorrow. And do what they say. Do not DIY
hotchocy
They absolutely can not claim your land as theirs. They would have to occupy it for 10 years unnoticed by you, and then during the application process to register it in their name you would be contacted and would have 2 years to respond and eject them from the land.
Firstly seek legal advice to determine any legal recourse for damage caused and a strongly worded warning letter sent from the solicitors to the CF's. As soon as you can remove their fences and return to them, it is your absolute right to do so. I would then erect your own fences if possible as well as signs stating trespass is not permitted. Keep checking regularly, if there is a repeat of the situation, defer back the the solicitor.
I have been working in land for 10 years so while not able to give legal advice I'm telling you what I have done for others in your situation.