From Britain’s point of view, the 1800 Act of Union was primarily a defensive measure to secure its western flank against the French. But after the defeat of Napoleon in 1815, the London government found itself in charge of a country of which it was profoundly ignorant. So, with true industrial-age logic, it set about creating official machinery to quantify Ireland and make it governable. Almost all surviving early 19th-century research sources emerged from this process: the Ordnance Survey, the Valuation Office, the censuses of 1821 and 1831 and much more.
One part of that administrative machinery, the Poor Law, is still with us. In 1838, 135 Poor Law Unions were created, covering the entire island. Each Union had an urban workhouse at its centre, responsible for providing the most basic and grudging short-term relief to the utterly destitute. The Unions were designed to be self-financing. The obligation to be pay for themselves overrode all others, and that is why they ignore county and parish boundaries – the area each one covered had to produce a similar amount of tax.
Property-owners in each Union paid the tax and in return could elect representatives to the Union’s Board of Guardians to oversee spending. So from the start, the Unions were geographically a hybrid of health service catchment area and electoral constituency. And, weirdly, that geographic hybrid exists even now.
For elections, the Unions were subdivided into District Electoral Divisions (DEDs), the areas used for the 1901 and 1911 censuses: those DEDs are still unchanged and in use in contemporary elections in rural areas.
Then, when universal registration of births, deaths and marriages began in 1864, the public health service took on the job. So subgroups of the DEDs were gathered into local registrar’s districts or “dispensary districts”, with anywhere from five to ten DEDs in each one. The Union was euphemised as a “Superintendent Registrar’s District”.
The Department of Health is still in charge of civil registration today. And after almost 200 years, its Superintendent Registrar’s Districts still largely cover the areas laid down by the old Poor Law Unions. They haven’t gone away, you know.
Peter Higginbotham’s wonderful workhouses.org.uk will tell you more.