As I always bang on about non these threads, in London (and elsewhere) it's pounds per square foot that matters. In this case it's £581per sq ft. Closer in, still NW London but zone 2 instead, it is more like £1000 to £1200 per sq ft, depending on land, decor, transport etc.
You have to assume these days that most people in London are going to renovate. You don't spend that kind of money on a home and not make it exactly how you want it. So decor isn't actually a big factor most of the time.