It is a term of every secure tenancy that the tenant—
may allow any persons to reside as lodgers in the dwelling-house, but
will not, without the written consent of the landlord, sublet or part with possession of part of the dwelling-house.
If the tenant under a secure tenancy parts with the possession of the dwelling-house or sublets the whole of it (or sublets first part of it and then the remainder), the tenancy ceases to be a secure tenancy and cannot subsequently become a secure tenancy.