Sorry Info Bank but I disagree. If the deceased tenant has already inherited the tenancy from his mother, there is no tenancy to pass on to a relative. Unless there is any protection under the Rent Acts, the tenancy will cease on the death of Noxy's friend's friend.
In any event, a secure tenancy under the Housing Act passes under that statutory regime, which as Ethel has already said, goes to a defined class of relative as long as they were resident with the deceased for 12 months or more. I do not believe a secure tenancy can be bequeathed by Will, it passes by operation of law.