Sectarian rivalries between Protestants and Catholics were a feature of the 1914-50s period and the Glasgow experience was replicated in many mainly working class areas of the industrialised lowlands of Scotland. The First World War (1914-18) saw a renewed influx of Irish immigrants, overwhelmingly Catholic, some of whom found work in occupational sectors hitherto regarded as Protestant "preserves". The impact of the immigration issue, along with that of the 1918 Education Act, served to heighten tensions in the post-war era. The Act provided for full state financial support for Catholic schools, and prompted a Protestant reaction against ‘Rome on the rates’.
The Orange Order, largely a society for immigrant Irish Protestants until the war, expanded rapidly as a result. On the Catholic side, the secret society of Irish origin, the Ancient Order of Hibernians, also thrived. Religious tensions intruded on local politics, and in 1933 the electoral strength of the Scottish Protestant League resulted in a split "Unionist" or "Moderate" (as most Conservatives labelled themselves) vote allowing the Labour Party control of the Council for the first time. The economic depression of the inter-war era only served to highlight the prevalence of sectarian criteria in the job market as scarce jobs were defended. In the realm of sport, the city's main football rivalry between Rangers and Celtic acquired even greater intensity on account of its sectarian underpinnings.
The impact of the Second World War and the increase in opportunities for social advancement in its aftermath, resulted in a less abrasive sense of co-existence. A significant rise in intermarriage generally altered the social dynamics in a more harmonious direction. Yet the strength of respective religious identifications and the continuing pervasiveness of "Orange and Green" cultural indicators, ensured that Protestant-Catholic relations remained uneasy.