Powers of the prime minister of the United Kingdom

The prime minister of the United Kingdom exercises functions in both the executive and the legislature, as the UK has a fusion of powers. Executive powers of the prime minister include obtaining at any time the appointment or dismissal of all other Government ministers, exercising the royal prerogative, setting the Government's policy agenda and priorities, and deploying the British Armed Forces overseas.

Source: Wikipedia — Powers of the prime minister of the United Kingdom (CC BY-SA 4.0)