A 38 mm badge with a grey background and "Team King John".
King John wasn't meant to be king. If his brother Richard (the Lionheart) had lived long enough to have a son then John would have merely been a Lord. But when Richard died without an heir the throne passed to John, who faced several rebellions during his reign and was forced to sign the Magna Carta. He was very unpopular, which is probably we've had no other kings called "John".