Sir John Oldcastle of Martyrs". Oldcastle was also a minor character in the early Elizabethan history play the "Famous Victories of Henry V" (c. 1586?), which is generally thought to have been one of Shakespeare's sources for his plays on Henry IV and Henry V. The genesis of "Sir John Oldcastle" is crucially linked to the fact that when Shakespeare's "Henry IV" plays premiered on stage in 1597–98, the character Sir John Falstaff was called Sir John Oldcastle. This is indicated by abundant external and internal evidence. The change of names, from "Oldcastle" to "Falstaff," is mentioned in seventeenth-century works by Richard James
The Shakespeare Code makes reference to the many debates about Shakespeare's sexuality. Shakespeare flirts with Martha multiple times during the episode, and ultimately composes Sonnet 18 for her, calling her his "Dark Lady". This is a reference to the enigmatic female character in Shakespeare's Sonnets, although Sonnet 18 is in fact one of those addressed to a male character, the Fair Youth. Shakespeare subsequently flirts with the Doctor as well, at which the Doctor observes, "Fifty-seven academics just punched the air," a reference to the debates on this subject. There is a running joke throughout the episode in which the Doctor creates an