The British railway system expanded exponentially during the nineteenth century. Its construction required an entire new workforce: in 1845 there were 200,000 men building 3,000 miles of new railway line.
The navvies (shortened from 'navigators', the canal-builders of the eighteenth century) building the railways came from across the British Isles. One third were Irish, seeking escape from famine. The railway-building boom of the 1840s coincided closely with an agricultural crisis in Ireland, and navvying provided a means of subsistence that would otherwise have been lacking. Many Irish navvies sent their earnings home while the Scottish and English lavished their wages on alcohol.
Having travelled to England seeking work, the Irish navvies were treated with contempt. The Presbyterian Scots navvies hated them, while the English had a reputation for fighting anyone but particularly the Irish. Religious differences were accentuated by the Irish being prepared to work for less money, thereby lowering wages generally.
Events reached a climax in early 1846, when an industrial dispute involving thousands of navvies spread across the north of England. The results were rioting, murder, confrontations with troops and widespread destruction. The experience of the Irish navvies is a graphic demonstration of the hostility that can be directed against migrant workers working on new technologies.