2016 minus forty years is ... 1976
Blimey you might be prior the 1977 change in legislation
I can confidently say that if you are on your original tenancy from 1976 then there is no one here ( bar Ubasses perhaps ) who has the fainted idea of inheritance of tenancies from that time ago
I only do the 1988 Act and I am virtually sure that that doesnt cover you ( unless you of course signed a new lease )
I mean you must have at least a protected tenancy under the 1977 Rent Act. I dont know what it was before that or waht the rights are
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/11445/138295.pdf
Shelter or CAB I think are your first stop