British Monarchy Records
Shortest length of Reign
King Sweyn Forkbeard
40 days

Lowest longevity of heir apparent
Henry, Duke of Cornwall, Son of Henry VIII & Katharine of Aragon
52 days

Youngest monarch at time of marriage
Monarchs that never married
William II; Edward V; Edward VI;
all lived & died unmarried
Edward VIII never married while he was king, but married after his abdication