Generally speaking, before 1914 the army was recruited from the top and bottom of society. For many years, 'respectable' working class families looked down on the type of man who filled the ranks of the army. The officer corps was recruited from a fairly narrow socially elite group, defined by money, education and birth. While it was possible for a working class ranker to be commissioned—famously, 'Wully' Robertson went from private to field marshal—it was difficult. There was little room for the middle classes, although many were to be found in the ranks and officers' messes of the Territorial Force. So Kitchener's expansion of the army in autumn 1914 brought into the ranks many men who in peacetime would never have dreamed of joining the army. In the 16th Manchesters (1st Manchester Pals) 'all classes mingled in the ranks. The packer from the basement and the commissionaire from the door were, as often as not, put in command of their seniors in the warehouse.'
Upper class ex-public schoolboys have come to symbolise the British army in the First World War. In reality the social base of the British officer corps began to broaden from the very beginning of the war, as Kitchener reached far beyond the traditional officer-producing classes to find leaders for his New Armies. By the mid-war period a rough meritocracy had emerged, in which rankers who had demonstrated leadership potential on the battlefield were sent for officer training more or less regardless of social background. From 1916 onwards almost every officer candidate passed through Officer Cadet Battalions, often based in Oxbridge colleges or similar places. Such men were given crash courses in officership, which included passing on the paternalistic ethos of the pre-war officer corps. Only about 2 per cent of those commissioned in 1913 had passed through the ranks, while about 38 per cent of officers demobilised at the end of the war had working class or lower middle class occupations.
In the course of the Great War 22.11 per cent of the United Kingdom's male population served in the British army, yet this did not represent a true 'cross-section' of society. Some geographic areas produced far more recruits than others. A battalion raised in a relatively thinly populated area, 9th Devons, included only about 80 natives of the county and had to be brought up to strength with men from London and Birmingham.