“It is the most important day in the history of Earth: the dawn of a new age of harmony or the start of its final war. The Doctor must face his most difficult challenge yet. It is a battle in which he cannot take sides and a day when nobody must die…”

Written by Chris Chibnall and guest starring Meera Syal (Goodness Gracious Me), the episode airs at 7pm on Saturday 29th May.