That means that normal people cannot afford to buy anything in London even with HTB which is a terrible policy the people who can afford to use it are already in the top percentiles.
A £600K property as a first time buyer requires you to have about £100K to get on a property ladder.
10% deposit for a 90% LTV mortgage is £60K, stamp duty is £17,500 (£20K from end of Sep 21) that’s already ~£80,000 then you have mortgage fees, legal fees, furnishing costs (since new builds don’t even come with blinds)…
The average salary in London is £41K, that leaves you with take home pay of about £30K after tax (if you have no student loans).
So a house hold of two people living in London has about £60K per year if both earn the average pay, £25K or more of which would go to rent per year, another £4000 will go to various utility bills and council tax, another 5-5.5K would go for travel (assuming you live within zone 1-4), then you have food, clothing and other living expenses, so if you are somehow lucky and can save up £10K per year that’s 10 years to save up enough for a median property which is most likely a 54 sq/m flat.
Add kids to this mix and well you are royally fucked.