An Officer Cadet Training Unit (OCTU) took either civilians or other ranks and trained them to be officers. The majority of infantry officers would have been trained through the Royal Military College, Sandhurst, which became the Royal Military Academy in 1947. However, during wartime, Sandhurst did not have the capacity to train all of the officers required. Therefore, specialist OCTUs were established and supplied officers to distinct arms of service, including machine gun battalions as a separate specialism to the infantry.
Prior to being commissioned into a regiment, cadets may have worn the insignia of the General Service Corps.
General Service Corps 
Infantry Training Battalions
Another source of machine gun training for prospective officers was the Officer Training Corps, which were officer cadet units at Universities and Schools. They were allocated places on specific courses during their holidays. The Easter Vacation in 1939 had one course at Aldershot between 17 March and 1 April for 30 officers and cadets of the Senior Division of the Officer Training Corps. These were announced in the Army Council Instructions when courses were available.
Prior to the start of the Second World War, in May 1939, officers for machine gun battalions were trained in the Machine Gun Wing of the OCTU (Infantry) and produced 13 cadets per month, out of a total of 122 cadets from the OCTU. This Wing required additional personnel as shown in the transcribed War Establishment.
Second World War
Once there was a need for greater numbers of machine gun officers, the Machine Gun Wing became its own OCTU independent of the rest of the infantry. This was established with a headquarters element, a headquarters company, one recruit company and four training companies, each with three platoons. The output of the OCTU was 95 trained cadets per month. They received 100 each month (and expected a loss of 5). The cadets would spend four weeks in the recruit company and then 16 weeks in one of the training companies.
Instructors for the Infantry and Machine Gun Officer Cadet Training Units were largely drawn from the regiments they were providing men for. When they were exchanged, they were exchanged with men of the battalions of the same regiment (as per Army Council Instruction 378 of 1940).
A complete transcript of the War Establishment for January 1940 is available to download:
In 1941, the Officer Cadet Training Unit for machine guns also trained officers for the Reconnaissance Corps. This may have been an additional OCTU, or possibly that based upon the Royal Northumberland Fusiliers, as this unit provided battalions for machine guns and reconnaissance.
With the growth of the Army and the need for more officers, it was decided in 1942 to standardise the first stage of Officer Cadet training this saw the establishment of 148 Pre-OCTU Training Establishment. The cadets would attend here for their initial training and then go to the specialised OCTU. It was located at Wrotham, Hertfordshire, and a company for machine gun officers was included in the Headquarters Wing.
By November 1942, there was a Machine Gun Wing forming part of the Motor Battalion OCTU; however, it could operate independently with a slight tweak of the War Establishment to ensure there were sufficient cooks.
With the introduction of the Divisional (Support) Battalion and Brigade Support Groups, the structure of the OCTU changed. The organisation from June 1943 was a basic company of six platoons after which they would progress to one of the two specialist training companies. Each of these companies included an MMG platoon for those going to Machine Gun Battalions and a separate MMG platoon for those going to a Support Battalion.
162 OCTU
As of October, 1942, the 162 Officer Cadet Training Unit was in existence at Lanark, Scotland, to train officers for the Machine Gun Battalions. By November, it is recorded as part of the York OCTU (previously No. 103) training both Motor Battalions and Machine Gun Battalions.
165 OCTU
This OCTU is recorded in 1942 as providing ‘general service training’ for officers, including a proportion to be sent to Infantry Machine Gun Battalions. It was located at Dunbar.
170 OCTU
As of June, 1940, the 170 Officer Cadet Training Unit was in existence at Aldershot, Hampshire, to train officers for the Machine Gun Battalions.
Sources
- Bayliss, Paul (2019), The History of the pre-Officer Cadet Training Unit [pre-OCTU] 148 Training Brigade, Wrotham (Vigo) 1942-1946 [online]. Stansted: Stansted & Fairseat History Society. Available from: https://stanstedhistory.org/landmarks-octu/ [Accessed 15 March 2021].
- The National Archives, WO 24/936, War Establishments 1939
- The National Archives, WO 24/937, War Establishments 1940 January to June.
- The National Archives, WO 24/945, War Establishments 1942 October to December.
- The National Archives, WO 24/947, War Establishments 1943 April to June.
- The National Archives, WO 24/948, War Establishments 1943 July to September.
- The National Archives, WO 293/24, Army Council Instructions 1939.
- The National Archives, WO 293/25, Army Council Instructions 1940.
- The National Archives, WO 365/150
- The National Archives, WO 365/163.
