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
John Oldcastle John Oldcastle, was Herefordshire's MP during the latter part of the reign of King Richard II. Oldcastle is first mentioned in two separate documents in 1400, first as a plaintiff in a suit regarding the advowson of Almeley church, and again as serving as a knight under Lord Grey of Codnor in a military expedition to Scotland. In the next few years Oldcastle held notable positions in the Welsh campaigns of King Henry IV of England against Owain Glyndŵr, including captaincy first over Builth Castle in Brecknockshire and then over Kidwelly. Oldcastle represented Herefordshire as a "knight of the shire"