Two Kent forts and their role in protecting England will feature in a new TV series.

Walmer and Deal Castle will be shown as part of Fortress Britain, coming to Channel 4 this month.

The new series examines Britain's preoccupation with being invaded, the root of it and how it has shaped the nation.

The episode based in Deal looks at Henry VIII's fear of an attack from Catholic Europe.

History professor Alice Roberts visits Walmer Castle where she examines a hoard of Tudor coins and a jousting scoreboard.

She will also discover how Henry laid the foundations of the modern secret service.

Colleague professor Danielle George will be at Deal Castle, where she will receive a lesson in cannon-power.

It will air at 8.30pm on Saturday, March 25.

Walmer Castle was built under Henry's orders as an artillery fort between 1539 and 1540, specifically to help guard against invasion.

The moated stone castle has a keep and four circular bastions and covers 0.61 acres.

It had 39 firing positions on the upper levels for artillery.

It cost a total of £27,092 to build this plus the nearby Sandown, and Deal Castles and all three were connected by earthwork defences.

Deal Castle was also moat stone and built over the same year.

It was constructed with a keep, six inner and outer bastions, had 66 firing positions for artillery and covered 0.85 acres.