What's in this bit of ceiling?

[burritofan]

Just moved house to a standard poky 3-bed c1900 terrace, kitchen at the back of the house, side return, small bathroom created in corner of upstairs box room, you know the drill.

Photos show floorplan and view of box room and bathroom doors from landing outside front bedroom. What's the big bulky bit of ceiling above the doors?

Bugger, floorplan won't attach. Hopefully you know the sort of thing

Could it be for old water storage tank?

Ooh, perhaps. I know from survey there is one but wasn't clear where. Hoping it's something we can remove, ideally ourselves because money.

We had a sticky-out bit like that in our dining room, house built circa 1909. We took the box away and found... nothing! Bare brick behind it, with some old plumbing, so we think it was a water tank or something.
Builder's coming next week to plasterboard the wall and make good the coving. Sounds daft when it's only that size, but taking it down's made a big difference to the room.

This is ours.

are there stairs of a half-landing?

Or is the ceiling lower at the back, with an addition roof sloping down?

I have a house on multiple levels, with a few interesting voids where the upstairs floors are different heights or there are steps, and one over the porch which has a false ceiling. I sometimes think of putting storage cabinets in them.

Thanks for responses!

Downstairs ceilings are lower at the back with a sloping but, and there's a half landing between the ceiling bit and me taking this photo.

CWST is in the loft, still supplying cold water to the bathroom though hot is on the combi boiler (for why?!). There's also a mysterious switch downstairs with a bit of wiring that could lead to this ceiling box and we thought did nothing but when the electrics were tested it did do something, though we know not what, so maybe old immersion tank?

We may never find out, though, as we're too occupied with a mains pipe burst in the kitchen and BED BUGS.