The first official census in Britain was conducted at a time of great national insecurity. Amid failing harvests and a war with France, MPs were concerned that the country could run out of bread to feed its population. The problem was, nobody knew how big that population actually was.
And so, on 10 March 1801, the first census of England and Wales was held (it counted 8.9 million people, roughly equivalent to the current population of London). Census questions may have changed somewhat in the interim – no longer are respondents asked if they are a “lunatic, imbecile or idiot”, as was the case in 1871 – but every 10 years since, with only one wartime interruption in 1941, a similar survey has been conducted to take a snapshot of the nation.
But for how much longer? The census may be the biggest mass participation event in the country, but there is a strong possibility that the last such poll across the UK has already been held.
Proposals by the Office for National Statistics (ONS), which conducts the survey in England and Wales, suggest the government intends to scrap the census in 2031, relying instead on a network of disparate public sector sources of data. Though authorities in Scotland and Northern Ireland conduct their own censuses, few observers expect them to resist a similar move if the ONS cancels first. Both bodies told the Guardian they would make their own recommendations in due course.
This proposal is not, in fact, new. It has been the “ambition” of the UK government since 2014 to conduct censuses after 2021 “using other sources of data and providing more timely statistical information”, Prof Sir Ian Diamond, the national statistician for England and Wales, notes in the ONS proposal document, adding: “We have reached a point where a serious question can be asked about the role the census plays in our statistical system.”
But as a period of public consultation closed this week, a group of 60 leading statistics academics published an open letter expressing their concerns. The ONS proposals were “clearly intended to lay the groundwork for abolishing the 2031 census”, they wrote – but just how accurate, comprehensive, accessible or democratically accountable would its replacement be?
Relying on “administrative data” – information collected by the state as a byproduct of another service, such as NHS information, school enrolment or tax records – “risks an increasingly fragmented and inaccurate data landscape”, they wrote, arguing that the ONS had not robustly tested its proposed replacement.
“We do often change the way that we do things, and of course there have been lots of changes in the census over the years,” said Alice Sullivan, a professor of sociology at University College London’s Social Research Institute and one of the signatories. “But it’s still incredibly successful in terms of response rates – there’s no sense that it no longer works.”
As for the proposed replacement, she says, “it’s not straightforward to take this patchwork of admin data and link it all together in an accurate way – particularly when there’s no harmonisation in the way different organisations are collecting data”. She cites information on sex and gender, collected in different ways by different agencies in recent years, as an example of datasets which may not be comparable to each other.
This may seem an arcane debate about a subject of interest only to data obsessives, but the census is extremely important for countless agencies, from local authorities assigning funding to services, to bodies monitoring ethnicity by region and those counting Welsh speakers, sexual orientation or numbers of carers. Some of those characteristics are not routinely monitored by agencies other than the census, say critics.
So why abolish it? In a transformed data landscape, the ONS argues, with huge data sources being collected daily, a once-a-decade survey may no longer be the best way to take a snapshot. “Our work … has shown that we can produce improved population estimates, and that we have developed methods for producing information about the population more often, more quickly and with better value than a decennial census,” Emma Rourke, one of the ONS’s deputy national statisticians, said in a statement. Surveys would continue to play a part in any new system, according to the body.
It is not, however, the ONS’s decision – the national statistician will make recommendations to the UK Statistics Authority, with the final decision to be taken by ministers. A committee of MPs is examining the issue.
There are plenty who see sense in the ONS argument. “Philosophically, I believe that moving to administrative data is the right ambition to have for 2031,” said Simon Briscoe, a statistician and former statistics editor at the Financial Times who has founded several data analysis startups.
However, he said, “I don’t think the ONS has yet demonstrated that it is up to the task of being able to use this administrative data to get decent records.”
The ONS acknowledges that some questions remain, but says it would work with other bodies to improve accuracy.
Critics suspect that cost – estimated at about £1bn for the 2021 census – is a key consideration for ministers. “I think there’s a sense of ‘we collect lots of data about people anyway, why on earth are we spending all this money once every 10 years?’,” said Mark Fransham, a senior departmental research lecturer at the University of Oxford’s department of social policy and intervention.
However, he said, it was far from assured that the proposed new system – which relies on datasets running on different systems, some based on archaic technology – would be any cheaper. “It’s quite possible that the work to bring together all of this data in a coherent fashion could easily be more expensive than the census.”
What about the accessibility of data to future historians or genealogists? “That’s a really good question,” Fransham said, “and the answer is we just don’t know.”
Beyond other considerations, he said, “something like 97% of the population take part in the census, and there’s nothing else that is [comparable]. It is one of those things that brings people together and gives them a sense of the society that they’re living in.”
