His reputation brought into disrepute by Captain Bagshaw, a competitor for the affections of Lady Jane Ponsonby, Bertram Oliphant West AKA "Bo" decides to leave England and join the French Foreign Legion, followed by his faithful manservant Simpson. Originally mistaken for enemy combatants at Sidi Bel Abbès, the pair eventually enlist and are helped in surviving Legion life by Sergeant Knocker, although only after they discover that when he is "on patrol" he is actually enjoying himself at the local cafe with the female owner, ZigZig.
The series uses the British comic traditions of music hall and bawdy seaside postcards. Many titles parodied more serious films, such as their tongue-in-cheek homages to James Bond, westerns, and Hammer horror films. Carry On Emmannuelle, inspired by the soft-porn Emmanuelle, brought to an end the original Carry On run.