The principle of the United Kingdom maintaining a relatively small Regular (or permanent) Army during peacetime, supported by a larger part-time Territorial Army had been in place for many years. The origins can be found in the raising of various militia or yeomanry regiments on a local basis, often for the purpose of maintaining public order. This was formalised in 1908 with the creation of the Territorial Force, as the U.K’s. reinforcements for the Army in times of crisis. The Territorial Force played an important role in The Great War, and was reconstituted in 1922 as the Territorial Army.

Between the wars, the Territorial Army provided fourteen infantry divisions, each based on a geographical basis within the U.K.. In 1936, two of these divisions were converted into anti-aircraft formations. With the outbreak of the Second World War, the Territorial Army again provided the main reinforcement to the Regular Army during this period. The Territorial Army was formally absorbed into the British Army on the 1 September 1939 as war was imminient, and this remained the case until April 1947.

The Territorial Army was reformed in April 1947, although the new commanding officers were appointed with effect from 1 January 1947. It was structured in the same manner as before, that is on a geographical basis with each divisional commander also acting as the district commander. The roles of the some of the formations were changed, with two armoured formations being created. In addition, an airborne division was formed. Some pre-war formations were amalgamated, so only six infantry divisions were reconstituted, but, there were some independent brigades also reconstituted. A significant number of anti-aircraft and field artillery regiments were also reformed.

The new Territorial Army formations raised in 1947 were:

16 Airborne Division, with headquarters in London;
49 (West Riding) Armoured Division – York;
56 (London) Armoured Division – London;
42 (Lancashire) Infantry Division – Manchester;
43 (Wessex) Infantry Division – Salisbury;
44 (Home Counties) Infantry Division – London;
50 (Northumbrian) Infantry Division – Newcastle;
51/52 (Scottish) Infantry Division – Edinburgh;
53 (Welsh) Infantry Division – Shrewsbury.

The ambitious order of battle for the post-war Territorial Army could not be sustained, and as early as 1950 (ie, three years after being reconstituted), several units (mainly artillery) were amalgamated. The Territorial Army continued however in this general form until it was abolished in 1967 and the Territorial Army Volunteer Reserve was created in its stead.