In message , at 17:50:04 on
Sun, 18 Jun 2017, Tim Streater remarked:
While any such block should have two staircases, where would one
actually put such a staircase - unless you sacrifice at least one of
the flats on each floor? I saw a floor layout the other day, looked to
me like any such staircase would be outside someone's window.

Most of the flats around here have two or more staircases.

The question was, where would you put a second, retrofitted, staircase,
on blocks like the one in question?

You'd have to use one of the 1-bedroom flats on each floor, reducing the
occupancy by about a tenth.
--
Roland Perry