 At the end of the war Greswell was placed on the reserve list of RAF officers.Upon recall in the 1950s he was promoted to group captain and his post war appointments included involvement in the air support planning for the British forces landings in Egypt during the Suez crisis in 1956.On promotion to air commodore in June 1964, Greswell was appointed as the 11th Commandant of the Royal Observer Corps during a period which saw the greatest reorganisation and upheaval in the organisation’s history.