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
Sir John McMahon, 1st Baronet family: his half-brother William MacMahon obtained the coveted judicial office of Master of the Rolls in Ireland through John's influence, although in the event he proved to be a popular and respected judge. He had no children but his title passed by special remainder to his brother Thomas. He is a minor character in Georgette Heyer's novel "Regency Buck", which shows him in a rather unflattering light. Sir John McMahon, 1st Baronet Colonel Sir John McMahon, 1st Baronet (c. 1754 – 12 September 1817) was an Irish-born politician and Private Secretary to the Sovereign 1811–1817. He was born in Limerick,