That's VERY aspirational pricing! Even by SJW standards, 22.5m is a lot for that.
Thing is, by the time you get to these prices, you expect a lot more for your money if this is a house to be lived in as a primary residence: absolute privacy, no bars/railings in front of the windows, no communal space, unlimited parking, a pool, much much more square footage, staff rooms etc. You can spend that money on an apartment in Mayfair and it would be feasible, if you're the type to have a primary residence elsewhere (an actual house, probably in a country setting in another country). You lock it up and go, the doorman and building staff will look after it. But this is a house that will require maintenance, presence, upkeep and isn't in the sort of location that occasional visitors to London would want. It's basically a centrally-located suburban house. It's a family home, to be lived in. That's a lot of compromising for a lot of money.