Answer:
The leader in majority party in the House of Commons is usually the Prime Minister.
Step-by-step explanation:
The Prime Minister of the United Kingdom is the British Head of Government, the de facto political leader and chief of the executive power.
The Prime Minister is formally appointed by the British monarch, who is bound by constitutional practice to choose the one most likely to be supported by the House of Commons (usually the leader of the majority party). The Prime Minister and the other members of the Cabinet are collectively responsible for their policies and actions before the monarch, the parliament, their political parties and ultimately the electorate.
Current Prime Minister is Boris Johnson, who took office on July 24, 2019 after Theresa May.