The idea is that two people on an average London wage should be able to afford to live in an average home in London. The truth is they can - if they can get the deposit together (which is trivial if you have parents you can live with for a couple of years, but if you've moved to London for work and your family lives 300 miles away your deposit savings go on rent). Perhaps they can't live in the most desirable parts of Chelsea, but there are affordable houses in the London area for a couple of 41k each.

Personally if I had to work in London, I'd look at buying a 2 bed house somewhere like Leighton Buzzard (30m Euston), Gravesend (22m St Pancras), Tonbridge (35m London Bridge), for about 250k.