Britain's Labour party Shadow Business secretary Rebecca Long-Bailey (C) and Shadow Chancellor John McDonnell (2R) listen as leader Jeremy Corbyn launches the party's election campaign in south London on October 31, 2019. Britain will go to the polls on December 12 in a bid to unlock the protracted Brexit deadlock. / AFP / Ben STANSALL
Labour leader Jeremy Corbyn launches his party's election campaign, watched by shadow chancellor John McDonnell (centre right). Ben Stansall / AFP

What would Britain look like under Jeremy Corbyn and his '70s sidekick John McDonnell?