The British Cabinet originated from ancient Anglo-Saxon councils and evolved over time. During the Tudor period, the Privy Council served as advisers to the monarch. The concept of a Cabinet developed under King William III with the rise of the House of Commons. The Cabinet solidified as the actual governing body under King George I and II when the monarch spent less time in meetings. Robert Walpole is considered the first Prime Minister of Britain in 1721 as the head of the Cabinet. The modern Cabinet is comprised of the Prime Minister and selected ministers, with the Prime Minister drawing up the list and agenda for meetings held twice weekly at 10 Downing Street in London.