Alice and other historians tell the story of Henry VIII's fear of invasion from Catholic Europe by looking at the physical reminders, including mighty castles and cannons.

Historians share the story of how Britain prepared for a Nazi land invasion during World War II, from tank traps and sticky bombs to the Home Guard, and the tragic story of a forgotten wartime heroine.

Danielle visits subterranean networks from where the country would have been run following a nuclear war; Onyeka learns how an upper-class spy network was passing nuclear secrets to the USSR.

The story of William the Conqueror's journey from invader to ruler of England; Alice discovers who the Normans really were; Danielle gets some 11th-century battlefield experience; Onyeka learns how William's coronation turned into a PR disaster.