2A period qualifies under this paragraph if it is a period during which, before the relevant time—
(a)the secure tenant, or
(b)his spouse (if they are living together at the relevant time), or
(c)a deceased spouse of his (if they were living together at the time of the death),
was a public sector tenant or was the spouse of a public sector tenant and occupied as his only or principal home the dwelling-house of which the spouse was such a tenant.