Former Labour leader and DECC secretary Ed Miliband made a surprise return to his old brief when he was appointed to Sir Keir Starmer’s shadow cabinet. But what influence will he have and how have his years in the political wilderness changed his thinking on energy issues? David Blackman talks to former colleagues - and adversaries - of Miliband about his views on decarbonisation, energy prices, nationalisation and what approach he is likely to take in holding the government to account.