Commissioned into the Indian Army in 1910, he served in France during World War I with the 34th Poona Horse and later the Cheshire Regiment, of which he was temporary commander of the 1st Battalion.

He then held a series of staff officer positions after the war before being promoted to lieutenant-colonel and receiving command of Probyn's Horse in 1935.

He was promoted to the temporary rank of brigadier and commanded troops in action in Waziristan in 1936 and 1937, being again mentioned in dispatches.

During World War II Baker was an aide-de-camp to King George VI and was promoted to the rank of lieutenant-general before retiring from military service in 1944.

[2] He was commissioned to the unattached List of the Indian Army on 20 January 1909[3][4] and posted to the 31st Duke of Connaught's Own Lancers on 29 March 1910[5] and was promoted to lieutenant on 20 April 1911.

He became a GSO2 with the Australian Military Forces on 1 January 1924 and was attached to the Department of the Chief of the General Staff in Australia.

[22] Promoted to the substantive rank of major on 20 January 1925, he was appointed Squadron commander with the 13th Duke of Connaught’s Own Lancers on 1 October 1928.

He became Director of Organization at Army Headquarters, India on 10 July 1940 and was appointed a Companion of the Order of the Bath on 1 January 1941.