National Statistical

The Office for National Statistics produces subnational population projections (SNPPs) to give users an indication of the potential future population size of English local authorities and health geographies. Today we’ve released our 2022-based SNPPs which will be widely used in planning, for example, health, education and housing. We don’t know exactly what will happen in a local area in 10- or 20-years’ time, so offer a range of scenarios, or variants, so decision makers can use the right projection for their needs. In today’s bulletin, we focus on the ‘migration category variant’. James Robards explains what this is and why we’re using this approach.

In January, the Office for National Statistics (ONS) produced its latest set of National Population Projections: 2022 based (NPPs). These projections give an understanding of the potential future size of the population, based on trends. They’re not forecasts or predictions. They don’t take into account potential future policy changes. They take into account current and past trends, and as those patterns change, we adjust our projections accordingly.

As I said in my blog in January, “population projections are only as good as the data and assumptions it is possible to feed in. Their real value lies in giving people a range of different scenarios to support the planning of services”. In our NPP release, we did just that, giving users, alongside a main or principal variant, a range of different variant projections they could use. These included possible scenarios based on low migration, low fertility and high life expectancy, among others.

Since that publication, we have produced new data about the main component of population growth – migration. May’s release provisionally showed that, in the year ending December 2024, migration to the UK had halved compared to the previous year. This meant, although in the long term we project annual UK net migration will settle around the 340,000 mark, in the short term our national projections were running too high. This is a reflection of the challenge in projecting the path from unprecedented levels of international migration seen over recent years to a lower long-term average figure and the uncertainty over the speed of decrease.

For both the subnational projections released today, and the NPPs released in January, the ‘migration category variant’ is a better fit with the international migration estimates we published in May while ensuring both sets of projections are consistent with each other. We now recommend the ‘migration category variant’ as the principal variant for England and the UK, and have engaged with a number of users in making this decision.

Therefore, the best indicator of the UK population for mid-2024 and mid-2025 is the ‘migration category variant’ projection. We will be updating our official population estimates for mid-2024 on July 30.

Making improvements to our release

Today’s release shows that the drivers behind the projected population increase vary significantly by area. In many local authorities, growth is mainly driven by internal migration. Internal migration of young people would furthermore contribute to the number of projected births. However, in many urban areas growth is driven by net international migration. Details on what is contributing to growth over the first ten years of the projection can be found in our new interactive tool, which we have built to help users easily understand projected change in their area.

It’s worth nothing that, at the local level, population change is also influenced by economic development and housing policies, factors which are not included in these projections. Therefore, we advise that our sub national projections should be used as a guide for users and have developed, as noted above, a number of other variant projections as part of this release.

For instance, we have added a zero net migration variant showing the implications of no migration to or from other parts of the world or other nations of the UK. The resulting variant projections from using these different assumptions show the potential implications for local authorities and users can use these to best suit their needs.

Incorporating the census

To produce quality population projections, we use a wide range of data to reflect the trends we are seeing in the population and give the best possible indication on the future potential directions. This includes Census 2021 data and rebased population estimates. Indeed, the release today benefits from the latest Census 2021 and national population projections data as inputs.

The new 2022-based SNPPs provide a detailed view of the potential future population of English local authorities, health geographies and regions to act as a common framework for planning purposes. We know it has been some time since our last release of SNPPs; during this time we have been focussed on national population projections and collecting all the necessary input data for this release. This is in line with feedback from users of population projections that we should incorporate all available data, including the latest census data, into the new subnational projections.

Alongside this new release today, in an accompanying report, we have also made comparisons of our past SNPP releases over the decade to Census 2021.

Coming up                                                                

From here we are focussed on concluding the next release of household projections, again for England, which are provisionally scheduled for release in August or September. We will be incorporating new data, including that from Census 2021 and the SNPPs, as a key input. Whilst this SNPP release covers England, work is underway on the development of SNPPs for Scotland and Wales with releases from the relevant statistical offices planned for the late part of the summer or early autumn.

Whilst we have increased the frequency of production of the NPPs over the last few years, we are aware that many users have a need for a shorter-term focus as an input for their forecasting. Therefore we are considering an alternative product focussed on the near term. Concentrating on the population over the next five years, this will give users a strong link from our latest population estimates and estimates of long-term international migration.

If you have feedback on any aspect of our work, please email pop.info@ons.gov.uk.