Shortest length of Reign

King Sweyn Forkbeard

​

40 days

Youngest monarch at time of accession

Mary, Queen of Scots

​

6 days old

Shortest length of marriage

Alexander III of Scotland & Yolande of Dreux

​

143 days

Shortest (unofficial) length of reign

Lady Jane Grey

​

9 days

​

although she was only proclaimed queen by the Lords of the Council on 10 July). The reign is disputed

youngest queen consort at the start of her reign

Isabella of Valois

(second wife of Richard II)

​

6 years 11 months and 25 days

Lowest longevity of heir apparent

Henry, Duke of Cornwall, Son of Henry VIII & Katharine of Aragon

​

52 days