Age structure and population change

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This section contains data on our past, current and future local population, including age, sex, birth rates and migration data. The data in this section is largely from the 2021 Census.

Population structure

The number of people living in our area is perhaps the most important single piece of data we can present. Many different services and businesses need to know the population to deliver services, manage finances, and plan for the future.

In 2021, there were 894,524 people living in Cambridgeshire and Peterborough on Census day.

Our best data at present comes from the 2021 Census, which took place on 21 March 2021 (please see the notes on data sources).The Census is repeated every ten years and so where possible we compare the most recent data with ten years previously to understand how our areas have changed over time. The Demography dashboard below allows users to see the Census data by age, including population pyramids which visually depict the age structure of the population. You can also choose to see data from the previous census in 2011. Please note that estimates of future population numbers are presented in a later section here.

East Cambridgeshire is our smallest district council area in terms of population, with 87,769 residents in 2021, and Huntingdonshire is the largest, with 180,834 residents. South Cambridgeshire has 162,106 and Fenland has 102,465.    

Cambridge City has 145,681 residents and the Peterborough City Council area (which extends beyond the city of Peterborough itself) is quite a lot larger than Cambridge at 215,669.

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It is interesting to see the variation in shape in the population pyramids for our areas. Cambridge City has a ‘Christmas tree’ shape to its population pyramid, with a large bulge in the younger adult age group, particularly young men, reflecting the large number of students in the city. This is very different to other areas in Cambridgeshire and Peterborough, many of which have a ‘dent’ in the population pyramid in the younger adult age groups, perhaps reflecting people’s movements away from home to study or live elsewhere. This has become more noticeable in 2021 compared to 2011.      

In all the population pyramids we see a lower proportion of people in the oldest age groups, reflecting a greater number of deaths in the population as people age. We can also see how there is a greater proportion of women than men in the oldest age groups, due to women’s longer life expectancy. However, later in this JSNA we will highlight how we are seeing more older people than ever before, a trend that is likely to accelerate, and cover some of the issues associated with this.

It is also interesting to note that most of our areas have a slightly lower proportion of residents in the youngest age band age 0-4, compared to older children.

Elsewhere on Insight, this dashboard takes Census data and visualises it at Ward or Output Area level which is likely to be useful for people interested in small areas. 

Population change in the last ten years

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This section and page 3 of the Demography dashboard deal with changes between the Census years; predicted future changes are covered later. Understanding recent population changes is important because of the need to plan for the likely numbers of residents now and in the future, and also the need to plan for the changing age structure of the population. A larger number of older people is likely to mean increased need for health and care services.  

Population change is driven partly by ageing in the existing population and birth rates (natural change), but also by people moving into and out of areas (migration), which in turn is affected by the local economy and changes in housing availability and new development.

All areas within Cambridgeshire and Peterborough have seen an increase in population between 2011 and 2021. Overall, there were 89,683 more residents in 2021 than ten years prior – growth of 11.1%.

Peterborough and Cambridge City have seen substantial increases, much higher than our other areas, and among the highest in England. Cambridge’s population increased by 17.6% and Peterborough’s increase was 17.4%. In comparison, the population of England as a whole grew much more slowly, by 6.5% in those ten years. For both Peterborough and Cambridgeshire, the population increase was much higher than had been predicted in ONS population estimates for 2021 (published prior to the Census). Cambridge and Peterborough’s growth rates were among the highest in England (Cambridge population change, Census 2021 – ONS)

Our other more rural areas saw less rapid growth, from 4.7% in East Cambridgeshire, 6.7% in Huntingdonshire, 7.6% in Fenland, to 9.0% in South Cambridgeshire.

The Demography dashboard allows users to see how the number of people overall and in each age group has increased or decreased between 2011 and 2021, and this can be viewed by district as well as for Cambridgeshire and Peterborough as a whole. Users can explore the dashboard to find the most relevant data for their needs, although key points are summarised below.

Overall, we can see that in Cambridgeshire and Peterborough there has been a big increase in the number of people in the older age bands. There are 25.6% more people aged 65 and over than ten years ago (page 3 of the Demography dashboard), which means an additional 32,066 older people. While there has been very limited growth in the age band 60-64, there has also been considerable growth in the numbers of people in their fifties (an additional 21,858 people aged 50-59).

In younger age groups, numbers of people in their forties have changed little, but there is an increased number of younger working age adults aged 25-39 (21,128 additional people). The pattern then is mixed with fewer people aged 20-24, little change in people aged 15-19, an increase in the number of children aged 5-14 (17,480 additional people), and then a notable reduction in young children aged 4 and under.

However, this overall picture hides some very interesting variations within our districts, with differences between our cities (Cambridge and Peterborough) compared to more rural areas. Cambridge City has a reduction in the numbers of people aged 85 and over, unlike the rest of our areas where this has increased considerably. Cambridge City has seen substantial growth in other age bands, except for a reduction in the number of young children aged 4 and under. Peterborough saw increases in nearly all age groups (except 20-24 year olds).

East Cambridgeshire has an ageing population; the numbers of people aged 50 and over (except for the group 60-64) have risen considerably but all age groups under 50 (apart from people aged 5-14) have reduced in number, and the population of very young children has fallen considerably (nearly 1000 fewer children aged under 5).

Similarly, Fenland has large increases in the numbers of people aged 50 and over (again except for 60-64 year olds). There was a mixed pattern in younger age groups with considerable reduction in the number of people in their forties. Huntingdonshire showed a similar pattern to Fenland and both areas saw a reduction in the numbers of residents aged 15-24 – possibly people moving away to study. South Cambridgeshire had increases in most age groups, with the biggest increases in the older age groups.


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The 2021 Census collected data on whether people were living at the same address one year ago, and if not, whether they had moved from within the UK or if they had moved to their current address from outside the UK. Many people will have moved a short distance within the area but the data does not distinguish between short moves and long distance moves within the UK. Page 4 of the Demography dashboard summarises the data on recent migration.

Summary points:

In Cambridgeshire 12.0% of residents had moved to their current address within the last 12 months, and in Peterborough this figure was 10.6%.  In Cambridgeshire, the overall rate is influenced strongly by Cambridge which had the highest proportion of people who moved to their current home in the last 12 months. In Cambridge, 20.2% of residents had recently moved to their current home, compared with 10.5% in England as a whole. Across the rest of the area there were few differences. As this Census was conducted in 2021, patterns of migration especially international migration are likely to have been disrupted by the COVID-19 pandemic. In ‘normal’ years we would probably have seen more internal and international migration, especially in Cambridge.

The ONS’ online Census 2021 visualisation tool allows users to identify small areas where high proportions of people have recently moved from elsewhere in the UK or abroad. We have not reproduced it here but their online tool is very useful. There are some small areas in Cambridge with very high rates of recent migrants.

Migrants from inside the UK:

Within the Cambridgeshire and Peterborough area the percentage of the population who migrated from within the UK varies from 8.6% in East Cambridgeshire to 15.9% in Cambridge City.  In East Cambridgeshire and Fenland, the value is 8.6% and 8.7% respectively which is numerically below the 9.6% of the population in England and 9.1% for the East of England region.

Migrants from outside the UK:

In Peterborough 1.1% of the population moved into the area within the last year from outside the UK. In Cambridge, the figure is 4.3%. For all other Cambridgeshire districts, the proportion of the population who moved into the area within the last year from outside the UK is similar to the East of England region (0.8%) and England (0.9%) except for Fenland, which is numerically lower (0.4%).

Country of birth

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Elsewhere in the JSNA we present data on languages spoken and ethnicity, but page 5 of this dashboard presents data from the 2021 Census on where our residents were born. Over two-thirds of Cambridgeshire and Peterborough residents were born in England (78.5% in Cambridgeshire and 69.8% in Peterborough – the figure for England as a whole is 80.3%). However, this varies considerably when looking at district council areas; just 59% of Cambridge residents were born in England, increasing to 86% in Fenland and East Cambridgeshire, 85% in Huntingdonshire, and 81% in South Cambridgeshire.

This page of the dashboard can present a lot of data, including the numbers of residents from each birth country and the nearest neighbour data. The top chart is a visualisation of the countries of birth for each (or all) of our district and city areas. It may be easier to see this data using the ‘focus’ mode on this chart (see user guide for guidance on this), and please note that areas where less than 0.5% of the population were born are not shown on the chart. The most common countries of birth vary considerably across our areas. Peterborough has a high proportion of people born in Poland (3.9%), Pakistan (2.9%), and Lithuania (3.6%). Fenland’s most common country of origin is Lithuania (3.4%), whereas in Cambridge India is most common (2.7%), followed by China (2.4%). In East Cambridgeshire, Huntingdonshire and South Cambridgeshire there are no countries outside England where 2% or more of the population were born.

More information

The ONS Census visualisation tool also shows the proportion of the population who were born abroad and in which country. 

Birth and fertility rates

Fertility rates are closely related to growth rates for an area and can therefore be a good indicator of future population growth or decline in that area. Fertility rates also contribute to predictions of the number of children and young people likely to require services over the next few years (although migration is also an important ). Birth rates are known to be higher in new communities (see here:


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Page 2 of the Fertility dashboard shows the general fertility rate (GFR) which represents the number of live births per 1,000 females aged 15 to 44 years. In 2021, the GFR was lower in Cambridgeshire at 50.3 than East of England (57.1) and England (54.3), whereas it was higher in Peterborough (59.1).

The five-year general fertility rate is available for districts (page 4 of the dashboard) whereas single year data is not available for districts. Cambridge’s 5-year GFR was low at 46 live births per 1,000 women, and Peterborough’s was highest at 75 – much higher than England (59).

Page 4 compares fertility rates with our nearest neighbours. Compared to their nearest neighbours, Fenland and Peterborough have notably high five year general fertility rates. Other areas do not stand out as particularly different in comparison to their statistical neighbours.

Page 5 shows the number of live births – a different measure to the fertility rate, but important for planning maternity and infant healthcare. Between 2012 and 2020, most areas have shown a steady decline in the number of live births, but there has been a small increase in 2021, apart from Peterborough where birth numbers continued to decline in 2021. Please note that migration is also an important influence on the numbers of infants and children in our areas.

Differences in birth rates at small area level

General fertility rate data is available at small area level; the Local Health dashboard opens in a new page and allows users to see shaded maps using these indicators (page 2). We can see that there were some areas in the north of Cambridge with very low fertility rates over 2016-2020, but also some areas of Cambridge with much higher rates. Rates in Peterborough tended to be higher. 


Next (Ethnicity and languages)