How do young people get on the property ladder in London?

I have just been watching a property programme on TV, and I was amazed to find that a 2-bedroomed flat in Hammersmith costs £540,000. On the other hand, you can get a three bedroomed detached house in the Newcastle on Tyne area for half that price.
What a dilemma for first time buyers - the well paid jobs are mainly in London. My eldest grandson pays nearly £1,000 a month rent for a two bedroomed garden flat in Brixton - he has to house share with a friend to be able to afford anything in London
I have read that about a third of first time buyers are given the deposit from their parents, who downsize to a smaller house to help them. I wonder if any of you have done this?