The Prime Minister is the leader of the political party that wins a general election and gets the right to govern. He is the head of the Government and chairs Cabinet meetings. He decides what policy areas to focus on and selects the people to run the different departments of government. These are called cabinet ministers. He also deals with foreign affairs and tries to find solutions to major issues, like terrorism.
He has some limited powers but his real power comes from being able to get things done by building consensus in his own party and with other leaders of the Government and Parliament. This is easier when his own political party has a majority in the House of Commons.
But even a Prime Minister with a big majority may find that his time is taken up by parliamentary management if the country is in wartime. Or if he has to deal with the problems of a weak economy or an energy crisis he has to make difficult decisions and balance different interests.
A prime minister has to manage the different strands of government work, so that he can focus on important themes and set out clear goals for his own Cabinet and the whole of the Government. This includes a big picture view of the nation’s needs and problems, such as tackling climate change. It also means minimising relaunches, reshuffles and announcements and being a force to be reckoned with in a moment of crisis.