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GLA 2022-based Population Projections
Demographic Update
August 2024
 
 
 
 
Executive Summary

This document summarises the key London-level results from the Greater London Authority’s 2022-based population projections.

As part of its 2022-based projections, the GLA has published:

Three variants of both trend-based and housing-led projections have been produced, based on different periods of past migration patterns and assumed levels of fertility. These variants are intended to cover a realistic range of potential future outcomes to help inform planning and decision making.

Key results

1 Overview of the projections

The GLA Demography team produces a range of population projections which are used to help inform planning and policy work within the GLA and across London. Projections are updated annually, incorporating the latest data as it becomes available. The 2022-based projections take as their starting point the most recent ONS Mid-Year Estimate (mid-2022).

This document provides an overview of the London-level results of the GLA 2022-based population projections, which include:

No household projections are included in the 2022-based outputs. The GLA is currently working to update its household projection model to include the results of the 2021 census and next plans to publish outputs as part of its 2023-based projections.

The two main types of population projection produced are trend-based projections, which are based on a cohort component model that uses past trends in births, deaths and migration to project future populations, and housing-led projections, which reconcile future population growth with assumed future housing supply.

Trend projections are typically most robust at larger geographic scales, such as regions or subregions. For applications that require finer spatial detail, the GLA recommends the use of the housing-led projections.

Several variants of both trend-based and housing-led projections have been published, based on different migration and fertility assumptions. The GLA recommends that users consider the results of multiple different projections to inform decision making, rather than relying on a single set of projected outcomes.

The GLA publishes information on methodologies and assumptions used in the projections on the London Datastore.

1.1 Variants

Three variants of both trend-based and housing-led population projections have been published:

  • 5-year low fertility
  • 10-year central fertility
  • 15-year high fertility

These variants differ in terms of:

  • the length of period of past patterns that are used as the basis for projected future migration trends - 5, 10, or 15 years
  • the assumed level of fertility.

Fertility rates for 2023 are based on the GLA’s provisional birth estimates, with the different variants reflecting the central, lower, and upper confidence intervals of the estimated births and fertility rates in the year to mid-2023 for each local authority. In a change from previous rounds, fertility rates remain fixed at their starting levels for the duration of the projection period. The variation between the low, central, and high fertility scenarios is relatively conservative – with assumed fertility rates spanning a range of approximately five percent in most authorities.

All variants use the same assumptions about future mortality rates.

Note: throughout this report, variants are referred to by length of migration trend only, e.g., 5-year trend rather than 5-year low fertility

1.2 Published outputs

Excel workbooks with outputs for each projection are available on the London Datastore. These workbooks contain population by single year of age and sex, together with summary components of change. Trend-based outputs include data for all local authority districts and regions in England and Wales; housing-led outputs include data for electoral wards (2022 boundaries) and local authorities in London.

A zip archive containing detailed components of change for all trend-based projections is also available to download.

At the time of publication, the London Population Projections Explorer was in the process of being updated with the 2022-based housing-led projections. This tool is intended to make it simpler for users to visualise the results of the projections, as well as to create and export custom charts and tables.

2 Projected population

2.1 Total population

London’s population is projected to grow from 8.87 million to between 9.26 million(5-year trend) and 10.17 million(15-year trend) in 2046, with the 10-year trend projection giving a figure of 9.83 million. This is a range of annualised of growth of 16 thousand to 54 thousand over the 24 year period to 2046.

Projected total population, London
Source: GLA 2022-based population projections

2.2 Annual population change

In the first projection year to mid-2023, London’s population is projected to grow by between 134 thousand (5-year trend) and 176 thousand (15-year trend), as a result of the high level of international migration.

Projected growth drops immediately in the following year to between 7 thousand (5-year trend) and 57 thousand (15-year trend), with 38 thousand for the 10-year trend. By 2046, projected growth falls to between 5 thousand and 34 thousand per year.

Past and projected annual population change, London

2.3 Age structure

London’s population is projected to age significantly over the coming decades, with the majority of growth expected at older ages and large proportional increases in the number of residents age 65 and over.

2.4 Working age population

The size of the working age population (taken here to be ages 16 to 64) in London is primarily determined by migration. The 5-year trend variant shows little change in the size of the working age population as a result of the high level of projected net out migration. The working age population continues to grow in both the 10-year trend and 15-year trend variants, albeit at a slower pace than in previous rounds of projections.

Working age population, London

2.5 Primary school age children

The standard age range of pupils in primary schools (Reception to Year 6) is 4 to 10 at the start of the academic year.

The size of this age group is determined largely by births over the preceding decade and the size of net domestic outflows of families from London to other regions.

The population of primary age children in London is estimated to have peaked at 790 thousand in mid-2017 and to have fallen to 735 thousand by mid-2022. In all variants, this fall is projected to continue until at least 2031, with numbers reaching minimum values of:

  • 5-year trend - 587 thousand in 2038
  • 10-year trend - 645 thousand in 2033
  • 15-year trend - 675 thousand in 2031
Population age 4 to 10, London

2.6 Secondary school age children

The standard age range of pupils in secondary schools (Year 7 to Year 11) is 11 to 15 at the start of the academic year.

The size of this age group is determined largely by births over the preceding decades and the size of net domestic outflows of families from London to other regions.

The population of secondary age children in London is projected to peak at 542-543 thousand in mid-2023, up from 535 thousand in mid-2022. In all variants, numbers are then projected projected to fall until at least 2036, reaching minimum values of:

  • 5-year trend - 406 thousand in 2044
  • 10-year trend - 445 thousand in 2038
  • 15-year trend - 467 thousand in 2036
Table 5: Population age 11 to 15, London

2.7 Population age 65 and over

The projected population age 65 and over is primarily determined by the size of younger cohorts set to join this age group and assumed future mortality rates.

The size of this age group in London was estimated to be 1.07 million at mid-2022 and is projected to increase strongly across all variants, reaching between 1.65 million (5-year trend) and 1.72 million (15-year trend) by 2046.

Population age 65 and over, London

3 Components of Change

Births, deaths and migration all contribute to London’s changing population. Natural change, which is the difference between the number of births and deaths, is the largest direct contributor to London’s population growth. Natural change is comparatively high in London because its age structure is much younger than that of the rest of the UK meaning more births and fewer deaths.

As noted above, London’s relatively youthful population is a result of established patterns of migration to and from the capital, which give rise to a net inflow of young adults and a net outflow of all other age groups.

3.1 Total net migration

Total net migration is the sum of all flows in to and out of an area. Historically, London has experienced very high levels of population turnover, with annual international and domestic flows in to and out of the capital estimated to have exceeded one million persons in some years. These flows typically tend to balance one another out, resulting in comparatively small overall net flows. Over the period 2002-2019 total net migration ranged between -46 thousand and 61 thousand.

COVID-19 saw significant disruption to migration flows both domestically and internationally. In particular, 2021 saw significantly higher than normal net outflows from London (-116 thousand). Flows in the initial year of the projection (2023) include provisional data from ONS on international migration at the UK level. The year to mid-2023 saw the highest net inflow of international migrants to the UK on record (627 thousand). This UK-level data has been used as the basis for a modelled net international inflow to London of 207 thousand for the year to mid-2023.

3.2 International migration

London experiences a consistently positive balance of international migration. Net inflows fell after the 2016 referendum to leave the European Union, and again during the COVID-19 pandemic, before rebounding to a record high in the year ending mid-2022 of 130 thousand, comprising of an inflow of 285 thousand and an outflow of 154 thousand.

Projected annual international flows for year ending mid-2023 are informed by ONS provisional UK-level estimates, with flows disaggregated by age, sex, and local authority in line with recent patterns. For London, this results in a projected inflow of 366 thousand, outflow of 159 thousand, and net flow of 207 thousand.

For years ending mid-2024 onward, projected international migration for each variant are based on the mean estimated flows over its reference period. Projected net flows range from 82 thousand to 91 thousand.

3.3 Domestic migration

The balance of domestic migration in London has been consistently negative for the last two decades, with more people leaving the capital each year for other parts of the UK than move to London.

For the year ending mid-2022, the estimated net domestic outflow from London was 126 thousand, comprising an inflow of 279 thousand and outflow of 405 thousand. By 2046, annual net outflows are projected to be between 112 thousand and 118 thousand.

3.4 Births

Annual births in London rose by approximately 30 per cent over the decade from 2002 to 2012. Annual births have fallen since the 2012 peak and in the year ending mid-2022 were estimated at 109 thousand. Differences in the projected number of annual births between variants are the result of both the number and distribution of potential mothers, and in assumed fertility rates. By 2046, annual births are projected to be between 106 thousand and 122 thousand.

3.5 Deaths

The same mortality rates are applied in each of the variants. Differences in the projected number of annual deaths between variants result from differences in the size and composition of the population. In the year ending mid-2022 there were estimated to have been 52 thousand deaths in London. By 2046, annual deaths are projected to be between 65 thousand and 67 thousand.

The impact of COVID-19 can be clearly seen in the data for years ending mid-2020 and mid-2021.

3.6 Natural change

Natural change is the annual balance of births and deaths and the largest contributor to London’s population growth. Annual natural change has fallen from a high of over 86 thousand at the start of the last decade to 57 thousand in the year to mid-2022, as a consequence of falling births and rising deaths.

By 2046, annual natural change is projected to be between 41 thousand and 55 thousand.

4 Interpreting the results

4.1 Why recent projections show lower levels of future growth

Recent rounds of GLA projections have shown progressively lower rates of future growth in London. This is a consequence of lower levels of annual growth in the population estimates on which the projections are based. In contrast to the rapid growth experienced between 2004 to 2016, when the population of London grew by more than 100 thousand per year, annual growth since 2016 is estimated to have been less than 20 thousand. As this period of lower growth has continued, its contribution to the patterns and trends projected forward in the model has increased, leading to lower projections of future growth.

The impact of recent lower growth is reflected most strongly in projections based on short periods of past data - illustrated by the very low growth projected in the 5-year trend variant of the current release. Future migration patterns in this variant are based on estimate flows for years-ending mid-2018 to mid-2022, a period during which London grew by just 8 thousand persons per year.

The latest outputs also project fewer births and more deaths than was the case for the previous round. Lower numbers of births are a result of both continued falls in the number of observed births in London, as well as methodological changes to how future fertility rates are determined in the model.

Greater numbers of deaths reflect a recalibration of mortality rates in light of recent data on observed deaths, which suggested that the assumed rates used in the 2021-based projections were overly optimistic.

4.2 Reasons for lower growth since 2016

Prior to the start of the COVID-19 pandemic, rates of population growth were already slowing as the result of several trends:

  • Fertility rates have been declining across the UK over the last decade, with annual births in London falling from their peak of 134 thousand in 2012 to 119 thousand in calendar year 2019. By 2022, annual births had fallen to under 110 thousand, the lowest level since 2003.
  • Net international migration to London decreased after 2016, due in part to the result of the referendum to leave the European Union.
  • Net domestic outflows from London to the rest of the UK, which had dropped sharply in the aftermath of the 2008 Financial Crisis, recovered over the following decade from a low of 32 thousand in 2009 to an average of over 100 thousand per year for the period 2016 to 2020.

The COVID-19 pandemic had a dramatic impact on both mortality and migration patterns, leading to the first annual falls in London’s population since the 1980s (see Population change during the pandemic).

While there is considerable uncertainty about how much the population fell as a result of the pandemic, the estimates used in these projections assume a decrease of approximately 80 thousand between mid-2019 and mid-2021. London’s population returned to growth in the year to mid-2022, increasing by an estimated 61 thousand, the long-term impacts of the pandemic on population trends remain unclear.

5 Comparisons with 2021-based projections

The GLA 2021-based interim projections were released in January 2023 and were the first to incorporate results from the 2021 census.

Beyond an updated starting point, the key differences in data and assumptions between the 2022-based and 2021-based projections are:

5.1 Population

The 2021-based projections gave a range for London’s 2046 population of 9.25 million to 10.27 million, compared to 9.26 million to 10.17 million for the 2022-based projections.

Projected total population, London

5.2 Annual population change

For year ending mid-2025 onwards, annual changes in total population for equivalent variants are similar for the 2021- and 2022-based projections, with differences of approximately 5 thousand per year. Lower net migration outflows for the 2022-based projections and higher natural change for the 2021-based, partially cancel one another out.

The majority of the differences in annual change occur over the period mid-2021 to mid-2024.

5.3 Total net migration

From year ending mid-2025 onward - when the 2021-based projections have transitioned to their long term migration assumptions - total net outflows from London are marginally lower in the 2022-based projections for the 15-year trend and 10-year trend variants, and almost 10 thousand per year lower for the 5-year trend variant.

There are much larger variations in annual net migration during the period mid-2021 to mid-2024 that arise due to differences in short-term assumptions between the two projection rounds.

5.4 International migration

After the initial short-term assumption period running until year ending mid-2024, net international migration for the 2021-based projections ranged from 64 thousand to 84 thousand, compared to 82 thousand to 91 thousand for the 2022-based projections.

5.5 Domestic migration

Net domestic outflows for each 2022-based variant are higher than for the equivalent output from the 2021-based projections. This is a consequence of the relatively large estimated net outflow for year ending mid-2022 (126 thousand).

5.6 Births

For the 2021-based projections, fertility assumptions from the ONS National Population Projections were used as a basis for future changes in local age specific fertility rates. For the 2022-based projections: low (for the 5-year trend), central (10-year trend), and high (15-year trend) estimates of fertility were produced for the year ending mid-2023, which were then held constant for the duration of the projections.

This change in approach results in lower assumed future fertility rates and contributes to fewer projected births in the 2022-based outputs.

From the 2021-based projections, births in London for the year ending mid-2046 ranged from 114 thousand to 127 thousand, compared to a range of 106 thousand to 122 thousand in the 2022-based.

5.7 Deaths

For both the 2021- and 2022-based projections, determining appropriate starting mortality rates was complicated by the large numbers of deaths that resulted from the COVID-19 pandemic. Rates for the 2022-based projections were recalibrated based on the estimated deaths for the year to mid-2022, generally resulting in higher overall levels of mortality and annual deaths than was the case for the 2021-based outputs.

5.8 Natural change

Natural change is generally lower for the 2022-based projections than for the 2021-based. Toward the end of the projection period, the differences in the annual change are approximately 5-10 thousand per year lower across equivalent variants. These differences are the result of:

  • higher assumed mortality rates and lower assumed fertility rates at the start of the projection period
  • changes to fertility methodology for the 2022-based projections, with rates held constant at their starting level

6 Data sources

6.1 Estimates back series

These projections take the ONS 2022 Mid-Year Estimates (MYE) population as their starting point.

The 2022 MYE was published in November 2023, together with a revised series of annual estimates for the period 2012 to 2021 that have been rebased to be consist with the results of the 2021 census.

The GLA considers the rebased estimates published by ONS to be problematic for use in projections due to the designation of significant amounts of change over the decade as Unattributable Population Change (UPC). Unless UPC is explicitly accounted for within the model, projections for local authorities with large amounts of UPC are liable to significant distortion.

Rather than dealing with UPC within the its projection models, the GLA’s preferred approach is to produce an alternative back series of estimates in which all population change over the decade is accounted for by conventional components of change.

Annual estimates of births, deaths, and internal migration for years ending mid-2002 to mid-2022 are used unchanged from the official series, as are population estimates for mid-2001, mid-2011, mid-2021, and mid-2022. International migration flows are modified from the published data for years ending mid-2002 to mid-2021, such that the conventional components of change result in a new series of annual estimates that are consistent with the official population data for census years.

6.2 Other inputs

Projected Age-Specific Mortality Rates from the ONS interim 2020-based National Population Projections (NPP) are used as the basis for assumed future changes in mortality rates.

Published data on births by age of mother are used together with modelled estimates of recent births to create estimated Age Specific Fertility Rates by local authority for the year ending mid-2023.

Provisional long-term international migration estimates (year-ending June 2023 edition) were used as the UK international migration flows for the year ending mid-2023. UK total flows were disaggregated by local authority, age, and sex, based on an average of the distributions from the previous five years.

 
 
 
For more information please contact the Demography Team, GLA City Intelligence Unit.
demography@london.gov.uk
 
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