Carry on Don't Lose Your Head (1967)

The time of the French Revolution, and Citizen Robespierre is beheading the French aristocracy. When word gets to England, two noblemen, Sir Rodney Effing and Lord Darcy take it upon themselves to aid their French counterparts. Sir Rodney is a master of disguise, and becomes "The Black Fingernail", scourge of Camembert and Bidet, leaders of the French secret police.