There's a 2 bed detached bungalow at the bottom of our road, sold for half that, but half the plot size. A lot for a 2 bed, but not so for the potentiAL, especially if you have the budget from London or down sizing.
That was my thought, you could do a lot, virtually unseen on that plat, if you're good at digging, link it to the original house as a period living space, bedrooms, gym, cinema, music room etc all in the hill.
nice windows. They'll be in a skip soon enough, very few people have good taste or...