He called himself "king of Great Britain" after gaining England's throne in 1603--he was already king of Scotland
... After her third 
marriage, to James Hepburn, Earl of Bothwell, Mary was defeated by ... the 
English throne on the death of Elizabeth I (March 24, 1603), he was already, as 
he told the... [DOC] [TLE] James VI and I - Wikipedia [PAR] James VI and I (19 June 1566  27 March 1625) was King of Scotland as James 
VI from 24 July 1567 and King of England and Ireland as James I from the union 
of the Scottish and English crowns on 24 March 1603 until his death.