A mate of mine's landlord has offered him a sum of cash for his flat and an assured tenancy for 40 years in a different flat in better condition rent free.
Based on the rent for the other flats he will be in profit after he's lived there for ten years.
Problem is the landlord has a buy-to-let mortgage and he won't ask the mortgage lender for consent (which my mate's solicitor has said he should do) - so does that mean he could get evicted if his landlord's property ever got repossessed?
The buy to rent mortgage presumably means he has to charge rent - but it probably depends on the exact wording of the mortgage deed.
The fact that the landlord won't ask the lender for consent would make me extremely suspicious, & you are quite right - your mate would definitely be evicted if the lender repossessed the flat. Advise him strongly not to accept.
I would very strongly advise against giving up an assured tenancy for a new flat. Best case scenario would be an assured shorthold, so after 6 months you could be given 2 months notice to leave. An assured tenancy is much more restricted in when a landlord can ask you to leave, so gives much more security of tenure. I would be asking for a decent sum of money to buy me out of an assured tenancy if I had one and the landlord wanted me out :)