Both, really!
Someone with £4.75m to spend has plenty of options. So why buy a house with that hanging over it?
Instead, knock it down. There’s potential because it doesn’t have a basement, and instead there’s a loft extension with reduced headroom.
I don’t know if there would be any chance of getting planning permission, but a developer could build a new house that goes down a floor or two.
There are £10m+ houses in Dulwich. Couldn’t someone with deep pockets turn this plot into one?