Who owns an un-documented cellar/bunker? (UK Law)

Question

A relative of mine purchased a house about 35 years ago. After a few years he discovered a bricked-up doorway leading to what was probably started as a WW2 bunker. It was abandoned and empty, and judging by some of the detritus (old papers, liter and sweet wrappers) it was last used in the 1950's

Over the years this cellar/bunker has been water-proofed, painted, ventilated and converted (to a high standard) into a workshop, playroom, gym, office and utility room and generally become part of the house.

Here's the problem. The rooms are quite substantial, they extend under two neighbors houses, three gardens, and even under a public road. There's no documentation on the bunker/cellar, they're not mentioned in the deeds or shown on any plans. The rooms make up more than half of the living area of the entire house.

My relative is likely to have to sell up and move into an old-peoples home.

Here's the question, who own these rooms? The only access is through the house, but there's evidence of a 2nd bricked up doorway which probably leads to the cellar of the house house two doors down (the houses are of a similar layout). The house is in an area that's rocketed in value since it was purchased, and if the underground rooms are deemed part of my relatives house then that more than doubles the living space and probably doubles the value of the house.

After having lived in and maintained these rooms for over 30 years can he claim any sort of squatters rights? Whats to stop the person who lives two doors down knocking through the wall into his entrance and claiming ownership of the parts of the rooms under his house?

Update - back when the bunkers were first found my relative did attempt to research the bunkers, but didn't find anything about who/why they were built.

Answer 1

Who Owns The Bunker?

Your relative obviously owns the cellar up to their land property boundary.

The people who own the other land would have originally been the owners of that portion of the bunker, assuming that it was not permissive (if it was permissive, an easement by estoppel probably would have arisen). So, then the question is, whether the people in the chain of title to the relative acquired ownership of that portion of the bunker by adverse possession.

Normally, adverse possession is acquired when someone occupies land under a claim of right that is open, notorious and hostile. While the use of the bunker would be "hostile" in this case (because the other property owners didn't have access to the bunker), it is not at all clear that it was "open and notorious". Indeed, apparently, the other land owners weren't aware that it existed. So, there would probably not be "squatter's rights" in this situation.

Also, adverse possession can't run against the sovereign, so to the extent that the bunker goes under public land (e.g. a public street), that also can't be adversely possessed and that portion of the bunker remains the property of the sovereign land owner.

@PaulJohnson in a comment to another post notes that:

It sounds like your relative has one of the secret bunkers built for the "Auxiliary Units" who were to wage guerilla war from behind the lines after a successful German invasion. bbc.co.uk/news/av/uk-37947840/…

If this were the case, and the government authorized its construction, there would probably be an implied easement that would allow the bunker to be the property of the person owning the entry to it, rather than the other property owners. But, as you note, proving that case would be difficult. It might be possible to scour declassified civil defense records from the WWII era to determine if this was the case, but you might need to employ an archivists or historian to get to the bottom of this question.

What if they sell it?

Suppose that they do sell it. What happens?

Since title is certificated in Britain, there would be no title insurance company to compensate the buyer if someone later claimed to own the property. Your relative would have a warranty of title inherent in the deed to the portion of the property that is legally described in the deed (unless the property were sold by a quitclaim deed specifically disavowing any promise that what was sold was owned by the seller), but that warranty would probably not include the portions of the bunker outside the boundaries of their lot because that is not included in the legal description of the property on the property certificate or the deed.

So, if it was sold, the buyer might not have any claim against the seller if the buyer did not get good title to the entire bunker, and would have no one to sue at all, if your relatives died before litigation over ownership of the bunker arose.

The buyer might sue your relatives for common law fraud if the bunker were described in the marketing materials for the sale, but if they were told that some of the bunker went outside the lot and that its legal status was unknown, or if the property was sold by a quitclaim deed, that suit would probably not be successful.

Other Options

Depending upon whether the owner is on good terms with his neighbors, the owner could probably buy the subsurface rights or some sort of easement to that property from the neighbors under whose land it runs, and might even be able to purchase such rights from the local council where it runs under a street.

Negotiating the price would be tricky. On one hand, it doesn't hurt the other owners at all. On the other hand, they have the power to deprive your relatives of all use of the property. Often deals like this are done for nominal consideration between people on good terms with each other, but for extortionate prices when people are not on good terms with each other.

Answer 2

Your relative owns the cellar up to their land property boundary. The people who own the other land own the bits that are on their land.

Technically, your relative is trespassing on their land by using the bits that aren't theirs.