Can landlord force improvements?

[inkmonkey2]

My father is a resident landlord living in a house where the second floor is a non-self contained flat (the stairs to the 3rd floor go through it but it share no facilities) . The flat is occupied by a tenant with an Assured Tenancy acquired by inheriting the tenancy by succession. There is no tenancy agreement and the tenant refuses to sign one.

The flat has had little or no work done to it since the 1950s. There is a toilet but no bathroom and only a rudimentary kitchen.

Can my father as the landlord force the tenant to accept the fitting of a bathroom and kitchen? (One of the rooms would need subdividing to make a bathroom)

Are there any laws regarding what is required to make a flat suitable for habitation?

Thanks

[jeffrey]

Easiest way: invite the Local Authority to exercise their statutory powers of inspection and thereafter to make an Improvement Order.

[westminster]

There's the Housing Health & Safety Rating System, which is backed up by the Housing Act 2004. Have a look at the operating guidance for local authorities.
http://www.communities.gov.uk/publications/housing/hhsrsoperatingguidance

As Jeffrey says, the environmental health officer at the council can inspect and order improvements.

BTW, I think it would be worth checking the status of the tenancy, as it doesn't sound like an assured tenancy when there is a resident landlord. Possibly a regulated tenancy if it began in the 50s...? This booklet may hold an answer.
http://www.communities.gov.uk/publications/housing/rentingrooms

Note that you can't change the tenant's status by getting him to sign a new tenancy agreement; in all likelihood it won't be binding.