World War II historians Al Murray and James Holland are at Longues-sur-Mer above Gold Beach where four imposing WW2 concrete casements housed German navy "Kriegsmarine" guns. They  look at the steps the Allies took to neutralise this position and find themselves marvelling at German engineering but questioning how deadly these guns were on D-Day.  CORRECTION: The photograph at 13:35 is not HMS Ajax but is photo taken from the HMS Ajax.