That leads to Post–World War II baby boom, which refers to the "UK Population Pyramid".
That brings me to Demography of the United Kingdom. The population pyramid wasn't interesting, but
The UK's population is predominantly White British
raised an eyebrow, so I followed the link. Found this:
For 2011, in England and Wales, the White British self-classification option included the subcategories of: White English, White Welsh, White Scottish and White Northern Irish. For the 2011 census in Scotland, the White British category was broken down into two different categories: White Scottish and Other White British. For the 2011 census in Northern Ireland, the White British classification did not appear, the only choice being ‘White’.
That just seems like a lot of going out of the way to avoid offending white people who disagree with each other on everything except their whiteness. Probably related to Brexit motivations, and to separatist Scotland tendencies and the like.
Also, this:
There were calls for the 2011 national census in England and Wales to include an extra subcategory so people could identify their ethnic group as Cornish.
That reminds me of a funny theme in W1A (on Netflix).