This Part of this Act is concerned with mortgages which—
(a) were created before the relevant date, and
(b) are regulated mortgages as defined in section 131 of this Act.
For the purposes of this Part of this Act, "relevant date"—
(a) in a case where, on 28th November 1967, land consisting of or including a dwelling-house was subject to a long tenancy which became a regulated tenancy on that date by virtue of section 39 of the Leasehold Reform Act 1967, means, in relation to that land, 28th November 1967;
(b) in a case where, on 22nd March 1973, land consisting of or including a dwelling-house was subject to a tenancy which became a regulated tenancy by virtue of section 14 of the Counter-Inflation Act 1973, means, in relation to that land, 22nd March 1973;
(c) in the case of land consisting of or including a dwelling-house subject to a regulated furnished tenancy, means, in relation to that land, 14th August 1974; and
(d) in any other case, means 8th December 1965.