There's also the point that banks want you to put down a sizeable deposit so that if the market crashes and you lose your job they can sell the house, recover their outstanding debt and you lose your deposit.

So you might be able to afford £1,200 a month in mortgage payments (which on a 30 year mortgage could mean you could borrow £400,000) but you'd need a 20% deposit, meaning you'd need to have saved up £100,000 to take advantage of it.

And even then, for £500k in London that's, what an okay 2 bed flat.