Yes the stairs downstairs are open plan, however I have building regs
approval and the staircase was clearly indicated on the plans, the new
stairs are however enclosed.

Whoops. Whilst you have obviously been subject to some sort of brain fart
between the architect and the BCO, you really should have the stairs
enclosed anyway. 3 storey buildings are a much more dangerous fire risk than
2 storey ones and it is much more likely to involve death if you jump from
that high up when things get hairy because the stairs are blocked. The
regulations do make sense.

Christian.