 Kirk was the successful candidate at the March 1965 by-election, and retained the seat until his death.Under Alec Douglas-Home's premiership, Kirk was Under-Secretary of State for War from 1963 to 1964.When the Conservatives regained power in 1970, Prime Minister Edward Heath appointed him as Under-Secretary for Defence for the Royal Navy from 1970 to 1973, during which time he visited every British naval establishment both at home and abroad.