For the purposes of this section "house", in the expression "house in multiple occupation", includes any part of a building which—
apart from this subsection would not be regarded as a house; and
was originally constructed or subsequently adapted for occupation by a single household;
and any reference in this Part to a flat in multiple occupation is a reference to a part of a building which, whether by virtue of this subsection or without regard to it, constitutes a house in multiple occupation.