This idea seems to have come from local london politicians rather than from the government, and it doesn't address the basic UK and UK infrastructure problem - namely that major infrastructure projects only really have worth when they are aimed at the southeastern quarter on England - that tiny southeastern fraction of the UK!
The UK needs to attract more business, and therefore improve infrastructure to the rest of the nation, thus spreading the wealth outwards from the southeast. in doing so it would also ease the pressure on greenbelt for housing and other development in what they call "the home counties".
It's really a question of what comes first, the demand or the infrastructure or vice versa. Having driven around Eastern Germany recently it seems their policy is to put in the infrastructure and then get the industry (jobs and presperity) to follow.