975. Meaning of 'tenancy at a low rent'.

'Tenancy at a low rent' means1 a tenancy2 the rent payable in respect of which or, where that rent is a progressive rent3, the maximum rent payable in respect of which:

  1.  

    (1)     where the tenancy was entered into before 1 April 1990 or (where the property comprised in the tenancy had a rateable value on 31 March 1990) is entered into on or after 1 April 1990 in pursuance of a contract made before that date, is less than two-thirds of the rateable value of the property4; and

  2.  

    (2)     where the tenancy is entered into on or after 1