After serving in Cape Colonial Forces in South Africa he joined the Grenadier Guards in 1893.

After his retirement from the army in 1922, he became Deputy Lieutenant of Suffolk and undertook various other public and charitable duties.

He transferred to the regular British Army on 3 May 1893 when he was commissioned as a second lieutenant in the Grenadier Guards.

[4] He fought in the Sudan Campaign in 1898, being Mentioned in Despatches for his part in the Battle of Omdurman,[5] and awarded the Distinguished Service Order on 15 November 1898.

[12] He participated in the battles of Belmont, Enslin, Modder River and Magersfontein, was badly wounded and received the Queen's South Africa Medal with four clasps.

[1] Loch returned to regimental duty in the Grenadier Guards on 23 January 1902,[13] and took part in a special diplomatic mission to promote British interests in Morocco in early 1902.

[28] Loch was given substantive promotion to lieutenant colonel on 13 March 1915[29] and continued to serve as the 28th Division's GSO1 during the Second Battle of Ypres.

[37] He was promoted major-general "for valuable services rendered in connection with the War" in the 1919 New Year Honours.

[46][47] He was still in the Reserve of Officers at the outbreak of the Second World War, but was not recalled for service.

[48] However, when the Home Guard was formed, he served as an Area Commander, despite being over-age, and this position being equivalent in rank only to a brigadier.

In 1931 this involved him in the case of Mick the Miller, which led to a controversial rerun of the Greyhound Derby.