802. Exceptions to rule that mesne tenancy must have been protected.

There are two exceptions to the rule1 that for a subtenant to retain his security against the head landlord the mesne tenancy must have been protected:

  1.  

    (1)     a long tenancy2 of a dwelling house which is also a tenancy at a low rent3 but which, had it not been a tenancy at a low rent, would have been a protected tenancy4 or an assured tenancy5 is treated as a statutorily protected tenancy6;

  2.  

    (2)     where the dwelling house is itself subject to a protected or statutory tenancy7 and forms part of premises which have been let as a whole on