Overview
The Census is incredibly important for central and local government both to inform policy makers and to plan the delivery of public services. As well as underpinning the population estimates the Census provides unequalled detail on population characteristics, helping authorities tailor services to reflect the needs of residents.
Census data is also vital in informing the distribution of resources and funding. Population estimates and projections, based on the Census, directly or indirectly influence around £4 billion grant funding received by London local government. They also impact billions of pounds of funding for the NHS, and the GLA (particularly through police and fire services) and other much-needed frontline services.
However, there is a concern that Census 2021 has significantly undercounted Londoners and that the data should be treated with extreme caution. As well as longstanding challenges over population counting in the capital, the Census 2021 was taken during the third national lockdown, at a time when many residents had temporarily relocated away from London.
Population change since 2011
The 2021 census suggests London’s population has increased from 8,173,941 in 2011 to 8,799,800, an increase of 626K people (7.7%). This is the third highest rate of increase of any region, and higher than for England as a whole (6.6%). However, this is far lower than the increase from 2001 to 2011 (14%) when London’s population saw the largest growth of any region between the censuses.
| Total population | Census 2021 | Census 2011 | % change 2011 to 2021 | 2020 mid-year estimate | Subnational population projections 2018, for 2021 | Projected increase from 2011 |
| London | 8,799,800 | 8,173,941 | 7.7% | 9,002,488 | 9,095,460 | 11.3% |
| England | 56,489,800 | 53,012,456 | 6.6% | 56,550,138 | 56,989,572 | 7.5% |
Figure 1, Population change between censuses.
The average for London hides a broad range of change: this ranges from an increase of 22% in Tower Hamlets to a decrease of 9.6% in Kensington and Chelsea. Kensington and Chelsea is one of three boroughs - along with Camden and Westminster to see a decrease.
Age profile
The census suggests London’s age profile has changed very little since 2011 and remains younger than the broader national average. In all other regions except London, there are now higher percentages of older people than younger.
Figure 2, Broad age bands comparisons
Households
The number of households with at least one usual resident has changed from 3,266,173 in 2011 to 3,423,800 in 2021, a 4.8% increase. This reflects how people live together, not the number of physical dwellings that they could live in. This average increase again hides significant variance in the changes at borough level, with a 19.0% increase in Tower Hamlets contrasted with the large decrease of -14.8% suggested for Kensington and Chelsea.
The household data also suggests potentially missing people, because if a proportion of homes were vacant when the census was taken, these would not show up in the data. While the census suggests an increase of just 156,000 households since 2011, the Department for Levelling Up, Housing and Communities reports 313,000 net additional dwellings were completed over the same period.
Figure 3, Households changes between censuses
Density
The density of people per square kilometre living in London has increased from 5,200 to 5,598 and is 13 times higher than the average for England. This reflects the far higher density in inner London of 10662 people per square kilometre.
Figure 4, Population density Census 2021 in persons per square kilometre
Response rate
The estimated response rate of 95% across London compares well to the response rate of 90% for the 2011 Census where one in ten London residents were missed by the count. Although this was as low as 89% in Westminster and Kensington, which had the lowest response rates in the country (two of the three London boroughs where a population decrease was recorded). This means that for London half a million people, or 1 in 20 people, may not be accurately reflected in the census figures.
Issues with the census
Undercounting London’s “true” population?
The 2021 Census population count of 8,799,800 is almost 300,000 (3.3%) lower than the Office for National Statistics (ONS) population projection of 9,095,460 for 2021, and around 200,000 lower than the ONS’s mid-year estimate for June 2020 of 9,002,488 (see Figure 5 and Figure 6 below).
London appears to have been disproportionately affected, with census population figures for 24 London boroughs being lower than the projections. Central London boroughs have particularly low figures compared with the ONS’s projections, with inner London boroughs on average 8% lower. For Camden and Westminster, figures were as much as 24% lower than the projection.
Figure 5, comparisons of population figures, source ONS
Figure 6, Census 2011 and 2021 vs Mid-Year Estimates and Sub-National Population Projections – London (Source: ONS)
The number of Londoners is likely to have been undercounted due to when the Census was taken in March 2021, which was during the third national lockdown in response to the Covid-19 pandemic. At this time, many residents – particularly students, young people on furlough, and migrant workers from abroad – may have temporarily relocated to family homes outside of the capital. It is difficult to quantify such effects, or predict how long they might persist, but there is strong evidence to suggest the trend in young people moving out of London during the pandemic has reversed (see Figure 7 below, where the dotted line represents the Census day).
Figure 7, payrolled employees by age trend
This is something that the ONS recognise in their description of the limitations and mitigations: “the coronavirus pandemic may have affected some people's choice of usual residence on Census Day, for example, students and in some urban areas. These changes might have been temporary for some and more long-lasting for others.”
Fully capturing all of London’s diverse communities has also always been challenging. In 2011, one in ten London residents were missed by the Census count. Reasons for this include language and cultural barriers, internal migration and churn, high levels of homelessness, and concentrations of buildings that are difficult to access. It is often the groups with the lowest response rates who are those most in need of local authority support. Published census figures include the best estimates of all population groups, but low response rates make it more difficult to accurately measure our most vulnerable residents.
These issues were worsened by the Coronavirus pandemic, meaning accessing hard-to-reach groups was even more challenging. Boroughs expressed concern at Census 2021’s emphasis on digital engagement, with most communications and support provided online rather than through face-to-face services or telephone support. The usual word-of-mouth communications routes were unavailable and public advertising may have been less effective as people were restricted to spending more time indoors. London has extremely high rates of digital exclusion, with an estimated 270,000 Londoners completely offline and 2 million having low levels of digital engagement.
Commentary
There are longstanding challenges around accurately counting population in London due to the capital’s high rates of homelessness, language barriers, and digital exclusion. Considering that this took place during a national lockdown, London Councils believes this combination of factors means the Census 2021 results are particularly problematic.
There is a risk, therefore, of a mismatch between the size and characteristics of London’s population as recorded in the Census compared with the situation under “normal” circumstances. We have asked that ONS exercises caution in updating population estimates to 2021 and 2022 making use of all available data sources to support the estimates so that population figures in areas, such as London, are not understated and that future funding allocations are fair. London Councils is keen for an ongoing dialogue with ONS colleagues over these issues, including working together with them and the GLA to sense-check against other administrative data sources, such as GP registrations, to develop an accurate and robust approach to measuring a fast-changing population.
Links to the data
The first data tables from the 2021 Census released on 28 June 2022.
An interactive report, including maps can be accessed here.
You can find out more about how the population has changed in different local authority areas and how they compare with others across England and Wales in the ONS: interactive article.
