Has anyone successfully won adverse possession on a piece of adjoining land?

[dontlookgottalook]

We have recently moved into a new property. At the end of our garden is the entrance to a WW2 air raid shelter, on top of which is a large shed. Access to all this is directly from our garden. This was constructed by the previous owners, however the land on which it sits is not within the boundary of the house.
It's been there over 12 years, and we have proof of this, as we have a letter from the council relating to this structure as the previous owners seem to have gotten planning permission for it (confusing as they didn't seem to own the land).
The person who owns the land cannot access our bit of it anymore from their house, as they are cut off from it due to a neighbour having bought their chunk of the land at the back of their garden off this person.
I'm just wondering if anyone knows anything about AP and how easy it is. If you meet all the criteria, can it still be rejected? Also, does it need to be done via with a solicitor?
TIA

You don't need to own land to get pp on it. Why can you not just buy it? Am I missing something here?

People on here are absolutely obsessed with adverse possession!
Don't you personally need to have occupied and proven use for many years anyway?
If I were you I would just ask for a price and negotiate.

The short answer is ... it depends.

The long answer is that it really does depend on a number of different factors.

There is a very tiny possibility that your neighbours house is still unregistered (but something like 95% at least of private homes are now registered). If that is the case, that would be where the 12 year thing comes in but I really would be surprised if your neighbour's property wasn't registered.

It is almost impossible now to claim adverse possession of registered land against the will of the true owner.

But there are some exceptions to the general rule. The one that might possibly apply to your situation is where neighbours share a boundary and, for some reason, the fence, wall, hedge or whatever is in the wrong place.

If the fence has been in the wrong place for at least ten years but you reasonably believed that it was in the correct place (eg you didn't sneak out one night and secretly move the fence to give yourself some extra garden) then you could make a valid claim for adverse possession.

Everything will revolve around the particular details of your situation. Was a fence ever put up? When your neighbour sold some of his land but left the bit adjacent to you was that because he also believed it was your land?

It will all depend on the details.

Yes thanks for responding all.
I have tried to contact the owner to offer to buy it but he's not responding, and as the piece of land has been occupied by our property for over the requisite number of years, we thought we could prove adverse possession instead. There is no way this person could ever access this piece of land as he is cut off from it.
It sounds like it's far more complex than i initially thought, but thanks for all your thoughts.