John of England

King John became King of England upon the death of his brother Richard the Lionheart in 1199. He was most notable for signing the Magna Carta in 1215. (PROSE: A History of Humankind)

While the real King John was in London taking the Crusader's Oath on 4 March 1215, the android Kamelion was being used in a plot by to sabotage Earth history by preventing King John's signing of the Magna Carta, an event pivotal to the development of parliamentary democracy on that planet. The plot was foiled by the intervention of the Fifth Doctor. (TV: The King's Demons)

Earlier in his personal timeline, the First Doctor had met John's elder siblings Richard the Lionheart and Princess Joanna in Palestine during the Third Crusade. (TV: The Crusade)

On one occasion, the Third Doctor briefly encountered a peasant from John's England who had been sent to London in the 1970s by a time eddy. The peasant told them that his king was Richard but John ruled England while his brother was in the Holy Land. (TV: Invasion of the Dinosaurs)

John was succeeded by his son Henry III. (PROSE: The King's Demons)

Behind the scenes
The following year, whilst eluding rebel forces, John sent his baggage train across the square-mouthed estuary on the northwest margin of East Anglia, only to have the British Crown Jewels it carried accidentally dropped and sunk in its waters. Tegan Jovanka's foreknowledge of this event was summed up in her assessment of John as "the one who lost something in ."