https://en.wikipedia.org/wiki/Tyneside_flat

and the Tyneside flat model...that sounds like a bit of a maze...depending upon which frontdoor you open...and of course, it is reminding me of EAGLE HOUSE....flat 4 had a staircase directly behind its frontdoor...

"The upper flat has a stairway leading from directly behind its front door, the other has a hallway beneath this, with the space below the stairway forming a small storage space."