The curse of dreadful DIY (about 99% of it, tbh, people of Britain put down your power tools).
The significant disjoint in London is that people treat £800k hours like they're £8k houses, so despite the eyewatering purchase price, expect weed-strewn driveways, tired decoration, peeling windows, and a general lassitude. It's not worth the effort, it's going to sell for a vast amount, so why bother. They evidently don't.
Also, stupid extensions, oversized excrescences clinging to the sides and back of houses – or balanced precariously on top – with no regard to size or style. Just because you can doesn't mean you should. People that rip out sash windows to replaced them with cheapest possible uPVC, those with bits of plastic in them that just makes them look even worse, like they're made out of some cheap Chinese Lego knockoff. I don't want to see a 2010 house that has plastic 'leaded' windows. Henry the fucking VIIIth did not live there. He would have everyone involved beheaded.
And, take a breath ian, the fucking car parks, entire gardens gone to tarmac, it must be like living in a Tesco car park. Shrubs, lawns, trees, all gone. Just a slick of tarmac or desert of grey paving so you can park eight cars. That's what you see every time you look out of your front window. A car park.
Of note in house-hunting adventures, I mentioned the smokers' sticky house elsewhere, but one splendid house we saw was literally splitting in half. Serious, had a crack that went up one wall, across the ceiling, and down the other. Not a small crack, the sort that made you feel unsafe standing in it. They'd sort of bodged with industrial quantities of polyfilla. £750k for a house that looked to be on its way to being two houses with interior open-air access.