Here’s an experimental page, not actually achieving very much.
I have long been interested in modelling the ageing population of the country and eventually I found the data at the Office of National Statistics, the ONS. It is not that I doubted the information was there, it was that this incompetent could not find it. Such an analysis is called age structure. In stats this would be (I expected it to be) called stratification, but it turns out that in this specialist world, stratification means looking at ethnicity. [Ethni City; that large suburb entirely housing people of the same ethnic background, noticeably different from the majority nationwide].
ONS provides the snippet to insert in the webpage, but I failed to make it work in 2017. Revisiting this page in 2020 after no success, the inseertion of rawHTML worked instantly. Success. Also 2020, I discovered Worldometers, who almost provide the information I have been seeking
Graphic by Office for National Statistics (ONS)
This shows population 1998 to 2038. You can compare two areas (even Blackpool). Clicking you cursor over the graph gives data point information, such that you could create your own model.
Notable on the page with the graphic, which shows the population born before 1971, are some steps in the population, sudden jumps in population. Both are immediately following the world wars, an additional 250 thousand immediately after the first and 200 thousand after the second. Look here for a range of similar products. The page I want to reproduce is this, where really I’d like to do my own (similar) modelling based on the data.
The ONS produces wonderful stuff and it is significant, I think, that such data is freely available. I found, for example, Z2 - Zipped population projections data files, GB and England and Wales, 2014-based (ZIP 2340Kb) Open data for GB, England and Wales 2014-based projections. Single year of age, sex with underlying data. Principal projections to mid-2114. Variants to mid-2039. Coverage: GB Geographical breakdown: Country with which I shall try to generate some share-able diagrams. Large .xml file, almost 34Mb, that Excel will read.
DJS 20151211
Extensive edits 20200405
Graphic by Office for National Statistics (ONS)
https://www.worldometers.info/demographics/uk-demographics/
Overview of UK population 2019 well worth a read, even if only a skim. It will be interesting to compare 2021's report with 2019's, being opposite sides of both Brexit and covid-19.
http://www.neighbourhood.statistics.gov.uk/HTMLDocs/dvc219/pyramids/index.html
https://www.ons.gov.uk/visualisations/nesscontent/dvc219/pyramids/index.html 2014-based projection of age pyramid allowing a variety of models to be explored. e.g. changing levels of migration or fertility or mortality. If the underlying spreadsheet is available, I didn't find it. Maybe this is sufficient. Search for interactive population pyramids.
National population projections 2019 includes downloadable spreadsheet content (.xlsx) equivalent to the pyramid above. Very straightforward; then you can do whatever you want with it. Of course, this doesn't tell you about migration, expected deaths rates and so on, but it gives you a healthy startpoint in terms of data for little effort. One assumes that the 2018 data is pretty close to correct.
https://cambridgeshireinsight.org.uk/population/ons-population-pyramid/ 2001-2016