It's expensive Bear, but your place (if you didn't move twice) increased in value from £375k to £500k (ish) over four years - a 33% increase in market value, consistent with price increases in the capital. It was fairly expensive to begin with.
(I speak as someone in a 2 bed flat in Zone 2, SE London, that cost £179k two and half years ago - now edging past £340k.)
There are cheaper properties available, in short. Not "forever homes", not perfect, possibly not in Zone 2, but people do what you did, and move out to Zone 4/5.
There are serious affordability issues in the capital for those on low pay, key workers, teachers and so on, but there is also a fair amount of hysteria. I posted on this thread to begin with because someone had posted a RightMove link to a dismal-looking place on the market for £600k that had been turned from one bedroom into three. Clicked on the link. It's in Hampstead. Well, no shit, Hampstead is expensive...