On Tuesday 28 July, the ONS released the long-awaited results of the 2021 Census. They’re the first of a long series of datasets and publications that aim at providing a picture of people and households in England and Wales. That first release looked at population numbers – which, alongside other metrics the Census provides, is incredibly important in our understanding of urban Britain.
Here are five things we have learnt from it.
1. Population has grown, especially in cities.
In 2021, there was a total of 59,597,500 people living in England and Wales and a majority of them lived in cities. Primary urban areas accounted for 56.4 per cent of this total population – corresponding to about 33.6 million city residents in both nations combined.
The country is increasingly urban as well: looking at changes in population numbers since the last 2011 Census shows that the urban population grew at a slightly higher pace than average (6.5 per cent change against 6.3 per cent). In absolute terms, an extra two million people live in cities compared to a decade ago.
2. The UK’s largest cities remain the same
It won’t be a surprise to anyone that, in terms of population size, London is still by far the UK’s largest cities – it now exceeds the 10 million inhabitants threshold. In second position comes Birmingham at 2.57 million, closely followed by Manchester at just under 2.54 million. The capital now accounts for nearly 17 per cent of the population of England and Wales. More surprising perhaps, this is four times more than the share accounted for by the UK’s second largest city, Birmingham – roughly four per cent of the total population.
3. Small and medium sized cities grew the most
Some large cities grew at a relatively rapid pace (like Bristol and Leeds), but in most, the growth has been either closer to the national average (like in Birmingham and Manchester), or more sluggish (like in Liverpool, Nottingham and Sheffield). In fact, the ten largest cities (excluding London) account for a slightly smaller share of the total population now than in 2011.
Table 1: Population in the largest cities (2011 and 2021)
||Change (2011-2021) %
|England and Wales
Source: ONS, Census 2021.
By contrast, the places that grew the most in population size tend to be small or medium sized cities, like Cambridge, Peterborough and Milton Keynes. All three have experienced growth of more than 15 per cent (more than double the rate for the national average).
Amongst other possible explanations, this is likely to be a sign that some of the UK’s largest cities tend to punch below their weight when it comes to housebuilding. In Cambridge, for instance, the total housing stock grew by 15.8 per cent between 2011 and 2020, compared to just five per cent in Manchester Birmingham and Sheffield.
4. There is a clear North-South divide in terms of population growth
As Figure 1 (and Table 1 shows) the large majority of cities with the highest population growth were located in the south of the country – particularly in the Greater South East. Meanwhile growth has been much slower in a number of northern cities, such as Birkenhead, Doncaster, Blackpool and Stoke. Population even declined in Sunderland (by about 0.5 per cent).
Figure 1: Fastest growing cities tend to be in the South of the country.
Table 2: Top 10 and bottom 10 population growth (2011-2021)
Source: ONS, Census 2021.
5. The Census numbers should be treated with caution
Of course, some of these results raise a number of questions that are yet to be answered. Population data is based on where the respondent was when Census was filled – but given this was in March 2021, at the peak of the second national lockdown, it is likely to paint a slightly distorted picture. For cities in particular, the risk is that is undercounts the total number of people who live in them in ‘normal’ times, as some city residents (in yet unknown numbers) might have decided to spend lockdown in their second house in the countryside, back home at their parents, or outside the UK.
Comparing Census 2021 data with population estimates for 2020 (modelled by the ONS and published every year) highlights some of these inconsistencies (Table 3). If both data sources were accurate, then they suggest that the population of Coventry, for example, shrank by about 9 per cent between 2020 and 2021. This is hard to believe, given estimates were showing Coventry was the fastest growing city in the past 10 years. Either the estimates are incorrect, or the Census undercounts the actual population size. This could be for instance because a number of students had gone home during Census. Other university cities, like Sheffield or Nottingham, see similar discrepancies, and the age breakdown shows unusual decline patterns for people aged 15-24, which supports this hypothesis. There are also inconsistencies the other way around: Cambridge’s population in the Census 2021 is 17 per cent higher than in the 2020 estimates – which is perhaps even more puzzling.
Table 3: Gap between the ONS population estimates for 2020 and Census 2021 data
||Top 5: Gap between the ONS 2020 population estimates and Census 2021
||Bottom 5: Gap between the ONS 2020 population estimates and Census 2021
It might be too early to gauge the extent to which Census data is reliable. This matters not just for those of us who like to get a clear and accurate understanding of cities but because a number of policy decisions are based on Census numbers – such as investment in schools, infrastructure, health services, jobs and training policies. Using inflated numbers for Cambridge’s population size, for instance, will affect the funding it gets from national government, while others might lose out if they’ve been undercounted, and investment decisions are likely to be skewed negatively.