It could also consider providing stronger support for the housing market, which outside of the London commuter belt remains highly depressed.

BBC: Business

But then, would high speed rail really move growth out, or would it make the whole country into Greater London's commuter belt?

BBC: Is London good or bad for Scotland?

The report says London's commuter belt now extends up to the end of the M3 and M11 to Chepstow on the M4 and increasingly those who can, move south.

BBC: NEWS | UK | England | Northamptonshire | London's growth 'swallows' south