In a scene in 'The Schizoid Man' No.24-Alison tells No.2 that there is an easy way to prove which one of the two 6's is the real No.6, as No.6 has a mole on his left wrist. The only problem being, No.6's mole has been removed! There is a precident set for this, and it takes place in the 1963 film ‘Carry On Jack.' Is the tale of Albert Poop-Decker, a newly commissioned Midshipman. The story starts with the death of Nelson who has said that Britain needs a bigger navy with more men. Anton Rodgers played Hardy. Poop-Decker (Bernard Cribbins) has taken 8½ years and still not qualified as midshipman but is promoted by the First Sea Lord as England needs officers. He is to join the frigate Venus at Plymouth. Arriving to find the crew all celebrating as they are sailing tomorrow, he takes a sedan chair with no bottom (so he has to walk) to Dirty Dick's Tavern. Jim Dale and Ian Wilson who plays his father carry the sedan chair.
Mobbed by women in the tavern as he is holding a sovereign aloft as advised by the men carrying the sedan chair, he is rescued by serving maid, Sally. She wants to go to sea to find boyfriend Roger but landlord Ned has let her down. She finds that Poop-Decker has not reported to the ship yet and is unknown to them so in a room upstairs, she knocks him out and takes his midshipman's uniform.
Poop-Decker wakes and dons a dress to cover his long johns and downstairs is shanghaied by a press gang, along with a cess pit cleaner named Walter Sweetly run by First Officer, Lieutenant Jonathan Howett and his bosun, Mr Angel They come to when at sea and are introduced to Captain Fearless who is anything but fearless. Poop-Decker makes himself known but there is already a Midshipman Poop-Decker aboard - Sally, in disguise. In attempting to prove his identity Poopdecker tells Captain Fearless he has a mole on his "whatsir!" Sally turns the table by declaring the man cannot be Midshipman Poop-decker because Midshipman Poop-decker doesn't have a mole on his "Whatsir!"
Okay, it's not a 100 pecent parallel, but the use of a mole to prove one's identity does set a precident, unless of course you the reader know of an earlier one.
I'll be seeing you