In message , at
22:14:43 on Tue, 20 Jun 2017, jim remarked:
Apparently there's a shortage of 1-bed property as an unforeseen
consequence of this benefit cap. So there are people suffering by living
in a surplus of 2-bed accommodation they can't afford to pay for.

Turning 20 of the 2-bed flats into a 1-bed plus stairwell will mean
everyone still has the bed they need, they will be better off, and the
building is safer. Win, win.

so the "new" one bedroom "flat" will have no toilet or cooking facilties -
unless it takes spaces from the one living room the remaining flat has?

Huh? The two-bedroom flat has six rooms at the moment.

Two bedrooms, a bathroom, a loo, a kitchen, and a living room.

The bedroom furthest from the living room is almost ideally placed to be
a staircase.

are they big enough for a largish stairwell? And do the flat layouts align on every floor to make it doable? And would the new stairwell have
communal access?

Volunteers for doing nige's research raise your hands.

It's OK, I did that research before posting the original suggestion. So
I can answer it off-the-cuff.
--
Roland Perry