If you somehow bought a house at a reasonable earnings multiple, say 4x earnings, then your house has appreciated essentially what you earned over the last 5 years. This is just math.
https://www.bloomberg.com/graphics/property-prices/london/ shows the median as having gone up around 6% in total since 2017. Trying a mix of neighbourhoods in that tool, I can't see any which are close to 100% up.
The situation is so bad that there isn't even housing stock available. You are generally better off moving out or buying whatever you can.
We looked at a home that sold for £415K in 2017 for example and we were outbid. It went for 865K
Flats aren't so hot, that's for sure, but there's been masses of price growth over the last 5 years on houses. There's a stunning lack of stock on the market.
[0] https://www.savills.co.uk/research_articles/229130/323909-0
12 Years underwater... optimistically given that its already not looking great for their 8% prediction for 2022