http://www.legislation.gov.uk/id/nisi/2006/1459

PART VAMENDMENTS OF THE RENT ORDER

Premises with a business use58

In Article 12 of the Rent Order (premises with a business use), for paragraphs (3) and (4) there shall be substituted–

3
Where it is possible to enter the part of the house used as a dwelling (“the residential part”) without passing through the non-residential part, Articles 3 and 4 shall apply only to the residential part.
4
Where it is possible to enter the residential part only by passing through the non-residential part, Articles 3 and 4 shall apply to the entire house.