DH and I have been renting a house in SE London for the past 4 years. The LL thus far seems sensible and values having a long term responsible tenant over potentially charging much more for rent (we have yearly increases but the local area has exploded due to the opening of a new train line.)
The house was bought in 2018 for £380K. The equivalent houses in the area range from £400K to £450K depending on exact location - ours is on a nice street and very close to the station so we imagine it would be the higher end. If the LL did the house up and sorted some niggly aesthetic issues he could sell for closer to £500K.
How much would you offer the LL? Obviously, he may not want to sell as he will never struggle to get rental from it, however if he was to sell to a sitting tenant, he would be saving a considerable amount by no empty property while selling, not having to pay to put the house 'right' etc etc. I do not want to be insulting but also...shy bairns get nowt!