How workable – and how expensive – might Labour’s renationalisations be?

John McDonnell says renationalisations won’t add to the public debt, and some academics agree with him.Labour has outlined plans to bring the rail, water and energy supply industries back into public ownership.Royal Mail will also be nationalised as part of a manifesto pledge to reverse some of the high-profile privatisations pushed through by the Conservatives in the 1980s and 90s, and by the more recent coalition government.