Prior to the creation of the position of deputy prime minister, a prime minister would routinely name a member of the cabinet to temporarily act on the prime minister's behalf while the prime minister was away from the regular duties of his job for a period of time, such as being out of the country on a working visit or a vacation. The delegate was thus a caretaker, whose role was to oversee the routine day-to-day functioning of the government and cabinet during the prime minister's absence; for example, in his capacity as acting prime minister, Mitchell Sharp ordered a precautionary one-day shutdown of government offices in Ottawa on August 20, 1970, as the storm that had spawned the Sudbury tornado headed toward Ottawa."Ottawa concerned". The Globe and Mail, August 21, 1970. p. 8. An acting prime minister did not otherwise have the authority to act independently of the sitting prime minister in a legislative or political capacity, nor would an acting prime minister be considered to have actually served as prime minister. As well the acting prime minister was not given the title The Right Honourable, even during the acting period, although some people who served as acting prime ministers may have independently earned that distinction for other reasons.
