 Complete the following phrase:  Elworthy was made Chief of the Air Staff on 1 September 1963. As Chief of the Air Staff, he worked closely with Secretary of State Denis Healey implementing the cancellation of the TSR-2 strike aircraft and the HS681 military transport aircraft programmes. He was promoted to Marshal of the Royal Air Force on 1 April 1967 and became Chief of the Defence Staff on 4 August 1967. In this role he oversaw the evacuation from Aden in November 1967 and had to respond to the growing 