<P> Since succeeding her father on 6 February 1952, Queen Elizabeth II has been head of state of 32 different independent states; currently, there are 16 states, called Commonwealth realms . Within the Westminster system in each realm, the Queen's government is headed by a prime minister . Appointment and dismissal of prime ministers are common reserve powers that can be exercised by the Queen or her governors - general . </P> <P> This list does not cover Commonwealth nations that are not Commonwealth realms, nor holders of offices of prime minister in colonies or sub-national entities such as states or provinces . </P> <P> The Queen has had over 160 individuals serve as her realms' prime ministers throughout her reign, the first new appointment being Dudley Senanayake as Prime Minister of Ceylon and the most recent being Scott Morrison as Prime Minister of Australia . Several of the Queen's prime ministers from various realms have been appointed for life to the Privy Council of the United Kingdom . </P> <P> Antigua and Barbuda became independent on 1 November 1981 with Vere Bird as the first prime minister . Bird had previously been Premier of Antigua . </P>

How many prime ministers in the queen's reign