I think this is just 'blame the poor for being poor' spin. If you are out of work, it's your own fault and nothing to do with mismanagement of the economy. And if you don't 'get on your bike', the government will paint you as a drain on society.
The environmental costs, as well as the practical difficulties, make this a poor joke. The South East, where most of the jobs are, is already short of water, with creaking infrastructure - if large numbers of people move, how are they going to get around? Because the roads and railways are already at capacity. And the only places left to build large numbers of houses are green belt or AONB or otherwise protected.
Also, if you encourage population shifts, you'll need new public infrastructure such as schools and GP surgeries. So you end up with more public money pouring into the SE and being taken away from areas that are already struggling.
And what about all these claims of investing in manufacturing instead of the finance industry? Can't see much room for affordable manufacturing industry in the SE - the cost of land is prohibitive. A landowner or developer can make far more money out of building houses than factories.