where do you get your figures from c m
if its a long term lease the chances are the rent will be what it was when they moved in plus inflation
if he has made any improvments new kitcken or windows for example he can go to the rent tribuneral and have the rent reassesed to take into account the improvments
there is a maximum the council will pay and for a retired couple i would think it likley to be between £100 and £200 rather than £350