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
Historical rankings of Prime Ministers of the United Kingdom of 258 academics who specialised in 20th-century British history and/or politics. There were 139 replies to the survey, a return rate of 54%—by far the most extensive survey done so far. The respondents were asked, among other historical questions, to rate all the 20th-century prime ministers (PM) in terms of their success and asking them to assess the key characteristics of successful PMs. Respondents were asked to indicate on a scale of 0 to 10 how successful or unsuccessful they considered each PM to have been in office (with 0 being highly unsuccessful and 10 highly successful). A mean of