Mr & Mrs buy a house and move into it.
Mrs dies and Mr doesn't want to live there anymore so he buys another house and lets out the first house.
When he does this he takes out a mortgage which is secured on the second house.
So whilst the mortgage is actually used to buy house two it is raised (partly) in order to enable house one to be let.
Can he claim the interst on this mortgage against the rent on the first house?
If not, would he be able to if the mortgage was secured on the first house?