To ask what this massive hole under our garden is?

[Greatbighole]

Husband just lifted up a slate in the garden and uncovered a concrete chamber which goes under our property and next door. It’s 6.5 feet deep. House was built in 1910, we moved in a few months ago. Didn’t come up in the survey or searches.
Any ideas?
Next door must know as they have built an extension over it but we don’t know them and don’t want to go knocking to ask right now, but obviously we will when we see them!
My husband accidentally dropped the slate into the hole which is what you can see in the bottom.

Have you got a delivery alley round the back? Is it a coal hole?

I'd assume an old coal hole too

Bomb shelter?

We used to have a WW2 concrete bomb shelter in our garden which looked like that inside.

Yes there is access from the back. Would a coal hole be that big? There no way of getting into the hole without a ladder

Coal cellar?

Does that fit with the age of the property?

Maybe something like an old air raid shelter?

Sorry, you said 1910 so yes.

Just had a quick Google (because I love stuff like this) and it could be a pre cast concrete air raid shelter.

I'd be a bit worried about someone's extension being built over that

Air raid shelter.

I dont know but I love shit like this so posting for updates. I think bomb shelter too.

It's huge! What are you going to do with it?

@DeepaBeesKit

I'd be a bit worried about someone's extension being built over that

I know! But having looked closer, they’ve put concrete joists across it on their side to hold the weight

Could it be an old septic tank?

Air raid shelter was my initial thought but it’s a small countryside town in wales (may not have even been a town back then) I assumed they would have only had air raid shelters in larger towns and cities

I wouldn't have thought it was a coal cellar or air raid shelter because there's no way down into it.

My air raid shelter has steps.

Maybe a cess pit?

Oh I would love that in my garden! I am guessing air raid shelter too.

I am assuming it’s structurally safe if neighbours have an extension over their bit! I would turn it into some kind of outdoor living space

It's too clean for a coal cellar, surely, and wouldn't be easy to get the coal back out. Air raid shelter looks more likely.

@Darkstar4855

Bomb shelter?

I'd assume not, as there's no way to safely close it over without the risk of dropping a slab on your head.

Definitely a coal hole being built in 1910 :).

A ces pit. It isn’t a septic tank as no soak away drainage from what I can see.

Yes I’d say that is almost certainly a coal cellar - there may well have been some kind of chute with doors built over the opening at one stage.

My parents found one of these and us kids thought it was so cool. They filled in in, I was gutted. If I found one I would make a secret room or at least use it for storage!