France: Cap Gris-Nez to Mont Saint-Michel

For the first time, Coast is in France on a journey following the shoreline of Pas de Calais, Picardy and Normandy to discover the surprisingly close connections to our neighbours across the English channel.

On Cap Gris-Nez (the Grey Nose), the closest point between Britain and France, Neil Oliver explores the hidden remains of a fortress built by Henry VIII in a desperate attempt to keep an English toehold on French soil. Dick Strawbridge unearths the story behind the ultra-secret map that stopped the D-Day landings sinking into the sands of Normandy. Dick meets 89-year-old veteran Royal Engineer Major-General Logan Scott-Bowden, who on New Year's Eve 1943 - a full six months before the invasion - swam onto the D-day beaches in the dead of night to take sand samples from under the noses of the Nazis.

Miranda Krestovnikoff has a close encounter with the bats that have set up home in bunkers abandoned by the German army. Mark Horton discovers how William the Conqueror taught the English the art of constructing castles, and why William looked to Normandy for the stone to build the Tower of London.

Amateur artist Alice Roberts packs her paints for a lesson in how to become an instant impressionist; she tries to capture the spectacular chalk cliffs at Etretat on canvas, using the impressionist style pioneered by Claude Monet on this stretch of the French coast. Nick Crane explores the white cliffs of France and finds evidence for the catastrophic 'megaflood' that separated Britain from the continent half a million years ago.

Finally, Dick Strawbridge learns how a revolutionary lens, invented by Normandy-born Augustin Fresnel, is now used the world over because it made lighthouses brighter and lighter.