Records of Prime Ministers of the United Kingdom transitions between reigns, eight Prime Ministers each served under two sovereigns: George III had 14 Prime Ministers serving during his 59-year reign (reigned 1760–1820), beginning with the Duke of Newcastle. The last incumbent, Lord Liverpool, was the only one appointed by his son (the Prince Regent) during the father's final incapacity to rule. In downward numerical order, numbers of Prime Ministers in office during other reigns are: Only six Prime Ministers came to serve office under sovereigns in whose own reigns they were born. The present Prime Minister, Theresa May, is the third Prime Minister to have been born in
Records of Prime Ministers of the United Kingdom to at least one other Prime Minister by blood or marriage. Two sets of father and son have successively held the office: The only brothers to hold the office were Henry Pelham, who was succeeded on his death in 1754 by the Duke of Newcastle. Pitt the Younger and Lord Grenville (who directly succeeded the latter in office) were the only set of full cousins to hold the office, their fathers being brothers-in-law. There have been three blood uncle-nephew sets of Prime Ministers: Lord Wilmington was two-greats uncle of Spencer Perceval, whose mother, Catherine ( Compton), Baroness Arden, was a