That's where the problem lies. I spend too much of my life screaming into the void about UK addresses and what is and isn't a town :)
It's just about possible to create dataset of towns, cities, villages from mixing and matching and cutting up other geographies from the ONS (e.g. their Parished and Unparished data (though Unparished is its own nightmare), then the ONS Built-Up Areas dataset but... that one cuts out all the non-built parts so Milton Keynes is bunch of big blobs around the residential areas).
But if you frankenstein it, you lose all of the formal connections that define other links, and if you try to cheat via geospatial join, you will link police forces to areas they don't actually serve.
For Swindon, you're kinda stuck glueing together (going from memory here - please correct me if I'm off) the Parishes of Central Swindon, South Swindon and West Swindon. But these will overlap with some villages so it's not a true count.
And that's a natural moment to lead on to the next critical point: how're we measuring population? (I always get that Father Ted speech scene in my head thinking about this, start speaking - then twelve hours later "And now, we move on to liars")
The UK census seems as good a measure as any.
Agreed, and it's a reasonable first reach for residential counts.
Problem is, it was last taken during 2021 - at the height of covid - and their estimates have been paying the price of it even since. Anything that touches on workday or employment they actively warn you away from, nowadays.
But then there's the elephant in the room: what if you're looking at somewhere like the City of London (the square mile one) where residential population is somewhere between 8,500 and 9,000 people?
EDIT: it slipped by me!
There is no single UK-wide census. NRS do Scotland's, last in 2022. NISRA handle Northern Ireland's census, last in 2021. And the ONS for England and Wales, last in 2021.