First appearance of Percival ("Percy") Sheldrake, Earl of Wordenshire, and his son Cyril as England's "Knight and Squire": Batman #62, cover-dated December 1950-January 1951 (but on-sale in October of 1950)
To be continued
They then returned four years later in Detective Comics #215 (cover-dated January 1955) as part of a group first referred to as "The Batmen of All Nations".
To be continued