E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The knave of clubs, short for Pamphile, the French word for the knave of clubs.
Dr. Johnsons derivation of Pam from palm, because Pam triumphs over other cards, is extremely comic. Of course, Pam is short for Pamphile, the French name for the knave of clubs.Notes and Queries (W. W. Skeat, 1 May, 1836), p. 358.