A person is qualified to succeed the tenant under an introductory tenancy if he occupies the dwelling-house as his only or principal home at the time of the tenant's death and either—
he is the tenant's spouse or civil partner , or
he is another member of the tenant's family and has resided with the tenant throughout the period of twelve months ending with the tenant's death;
unless, in either case, the tenant was himself a successor, as defined in section 132.