Fine, but why comment on the thread. Are you going to suggest the OP moves the flat to Scotland and sells it for 40k?
Well, I suppose to say that the flat is massively overpriced if you are wanting to exchange £550k for a lovely place to live with loads of living space, a garden and up to date furnishings.
If you think about a couple in their early thirties looking for somewhere to live, what is appealing about London right now? There's nothing going on, many jobs are WFH or ceasing to exist. The arts scene has been decimated.
If you wanted to buy an ex-council flat you could get this one for less than half price in Sheffield, an area with plenty to do in none Covid times that is currently being overrun by buyers fleeing from London:
www.rightmove.co.uk/new-homes-for-sale/property-94604537.html
Probably loads of similar properties in Manchester, Birmingham, Leeds etc where you can WFH and have a good life.
Bad luck for the OP, but a dated flat in a nice area of London is not worth what is was a year ago, and IMO is unlikely to be for a long time.
It seems all the posters from London are convinced o it's worth, probably because they don't want to face reality that they are sitting in overpriced property due a correction