Owain,

The floors are set unusually high above the basic ground level: the plans
show three steps, with the topmost one being one riser height below the
interior floor. That's to say four risers have to be negotiated to get
inside the house.

GB,

Aren't these two completely separate tests,
and you have to pass both?

That's a good point. My recollection now is that plans were submitted to
both planning and building control; I'll check back through the files and
see if I'm right.

I don't necessarily want to begin the steps directly from the threshold, but
the layout of the garden at that point does make a sizeable level area
tricky to fit.