When George arrived in England, he knew little about
British politics nor could he speak very much English.
George therefore became very dependent on the Whigs,
who had arranged for him to become king. This included Walpole
who was made Chancellor of the Exchequer in 1715.

King used to ask Robert Walpole to speak on his behalf. So Walpole had become the important,
prime person. Thus he got the title, Prime Minister. That habit of requesting the prime person to assume
the Prime Minister office and run the Government on King's or Queen's behalf is still being followed.

Queen invites or appoints the leader of the largest party to the post of the Prime Minister.
In India, instead of King or Queen the President invites the leader of the largest
coalition to form the Government.

Walpole was such a powerful figure in the government he became known as
Prime Minister, the first in Britain's history. He was also given 10 Downing Street
by George, which became the permanent home of all future Prime Ministers.