Career
He was the oldest of Perrers" three acknowledged illegitimate children by her royal lover. During the abortive Castilian campaign led by his half-brother the Earl of Cambridge in 1381, John led a contingent of English soldiers. After his troops went unpaid, John led them in a mutiny.
He may have been only a figurehead for the mutineers, though, as he (unlike the other conspirators) went unpunished afterwards.