Who is the longest serving

heir-apparent in British history?

INCORRECT

Image in the public domain.

William IV

HH

William IV (21 August 1765 – 20 June 1837) was King of the United Kingdom of Great Britain and Ireland and King of Hanover from 26 June 1830 until his death in 1837. The third son of George III, William succeeded his elder brother George IV, becoming the last king and penultimate monarch of Britain's House of Hanover.