Premium tenancies – difficult to distinguish the name from another concept called a Priemium Lease. Note that a lease in this context, is a synonym for a tenancy agreement, contract to rent, etc. Yet the two homonyms have diferent perceived meanings
A premium tenancy is one where a deposit is paid by the tenant to the landlord, the value of which is more than 1/6th of the anual rent. 1/6 = 2 months = just over 8 weeks.
This might affect a student landlord charging 2 months rent equivalent as a deposit, allowing a summer rent discount (retainer) thereby proportionally increasing the deposit to more than 1/6th. This is why deposits seldom exceed say 6 weeks rent in value.
In my 27 years letting I (Bob Leydon) have never come across a premium tenancy or even a reference to one.