Prime Minister's Office (Sri Lanka) the Parliament. The office of prime minister was formed in 1947 with D. S. Senanayake becoming the first Prime Minister of Ceylon. It consisted of a Secretary (Permanent Secretary) and an Assistant Secretary, who were officers of the Ceylon Civil Service, and a Private Secretary, along with clerical and support staff based at the Senate Building along with the Senate, Cabinet office and the Ministry of External Affairs and Defence. Since 1960 the prime minister's office has been based at Sirimathipaya Mansion on Sir Ernest de Silva Mawatha (formerly Flower Road), Colombo which was the former residence of philanthropist Sir
Prime Minister of the United Kingdom origins of the position are found in constitutional changes that occurred during the Revolutionary Settlement (1688–1720) and the resulting shift of political power from the Sovereign to Parliament. Although the Sovereign was not stripped of the ancient prerogative powers and legally remained the head of government, politically it gradually became necessary for him or her to govern through a Prime Minister who could command a majority in Parliament. By the 1830s the Westminster system of government (or cabinet government) had emerged; the Prime Minister had become "primus inter pares" or the first among equals in the Cabinet and the head