Colonel Walter Stewart was educated at the University of Aberdeen, from where he qualified MB ChB in 1934. He was House Surgeon at the Royal Infirmary, Sheffield when on 1 September 1936 he applied for a Short Service Commissions in the RAMC. He entered the RAMC College Millbank on 31 October 1936 and the RAMC Depôt on 1 January 1937.
23 Oct 1936 Appointed to a Short Service Commission Lieutenant RAMC. His appointment was antedated to 23 October 1935, under the provisions of Article 36, Royal Warrant for Pay and Promotion, 1931, but did not carry pay and allowances prior to 23 October 1936.
23 Oct 1937 Promoted Captain RAMC with seniority from 23 October 1936.
1937–1942 Served in Palestine (Middle East Force).
8 June 1939 Appointed a Member of the British Empire (Military Division) in the King's Birthday Honours list.
22 July 1940 Acting Major RAMC.
23 Oct 1941 Appointed to a Permanent Regular Army Commission Captain RAMC with retained seniority.
1942–1943 Served with the Persia and Iraq Force.
1944–1946 Served in North West Europe.
14 Oct 1944 Acting Lieutenant Colonel RAMC.
14 Jan 1945 War Substantive Major RAMC.
23 Oct 1945 Promoted Major RAMC.
1948 Commanding Officer 129 Field Ambulance British Army of the Rhine (invalided).
Specialist in Army Health and Hygiene.
1950–1952 Assistant Director of Medical Services (ADMS) HQ BAOR.
22 Sept 1950 Promoted Lieutenant Colonel RAMC.
1953–1955 Assistant Director of Army Health (ADAH) HQ Scottish Command.
1955–1959 ADAH and ADMS GHQ Middle East Land Force.
14 Nov 1955–31 Mar 1957 Temporary Colonel L/RAMC.
23 Oct 1958 Promoted Colonel L/RAMC.
1959–1961 Deputy Director of Army Health HQ Northern Command.
1961–1964 Assistant Director General Army Medical Services War Office (AMD 2).
1962 Appointed an Officer (Brother) in the Most Venerable Order of the Hospital of St John in Jerusalem.
1964 Consultant in Army Health.
1964–1967 Deputy Director of Army Health HQ Eastern Command.
Malta Feb 1966 Arrived from England, as ADMS HQ Malta Command.
Malta Feb 1967 Assistant Director of Medical Services HQ Malta Command and Assistant Director of Army Health HQ Malta Command.
Malta 1 Sept 1968 Left Malta on retirement from the service.
- Entry No: 1633. Drew R.,1968. Commissioned Officers in the Medical Services of the British Army 1660–1960, Vol II Roll of Officers in the RAMC 1898–1960 London, Wellcome Historical Library.
- Succession Books Vol XXIX, Returns of statement of service of RAMC Officers.