If you ask the random person in the street "what's the smallest city in the UK", most people will give you a funny look and move on, muttering something about not having any change right now. Of the rest, I bet you two shiny brass buttons that the most popular answer would be "St David's".
The Welsh city is well known for being pocket sized. This is a place of just 1,841 people. The town of Croydon, which has been rebuffed for city status on at least five occasions, has a population 120 times larger than tiny St David's.
And yet, by some measures, the UK's smallest city is right here in London, and often gets overlooked in that sense.
It is, of course, the City of London — the financial and ancient centre of London. How does this "Square Mile" stack up against fellow flyweight of St David's?
As we've already seen, St David's has a population of 1,841, according to the 2011 census. This is the settled resident population. It'll swell come summer, during tourist season.
The City of London is a much bigger on this metric. The 2011 census had the place at 7,375. That's still a minnow in the grand scheme of things (it is the third smallest population for a city behind St David's and St Asaph), but almost exactly four times bigger than St D. It's estimated to be a bit larger now, too — over 9,000 — thanks to several large residential developments in the Square Mile. And if we throw in the daily flux of commuters, even post-covid, then the number in the City on a given weekday jumps 50-fold.
Winner: St David's is the UK's smallest city by population size.
By urban size
This is where it gets more complicated. How we define the size of a city is open to different interpretations.
We might take the extent of the built-up urban area. In this case, those 1,841 people of St David's nestle into an area of just 0.23 sq miles. Many villages in the UK are larger. The City of London, by contrast, is 1.12 sq miles, a wee bit larger than its sobriquet of the Square Mile.
The disparity is even greater if we consider habitable space. The Square Mile contains dozens of skyscrapers that could house the entire population of St David's. The Welsh city, on the other hand, has virtually no buildings above the second storey, other than the cathedral.
Winner: St David's is the UK's smallest city by built-up area.
By local authority size
But stop right there. Most towns and cities don't end with the last house. Their local authority boundaries extend out into the surrounding countryside, often to include smaller settlements. This is the case for St David's, which not only controls a significant chunk of surrounding land, but also oversees the sizeable Ramsay Island and many smaller islands. Wikipedia has a handy map:
Suddenly, St David's doesn't look so tiny. It'd take you most of a day to walk the length of just the mainland stretch.
The City of London, by contrast, is self-contained within its boundaries of 1.12 sq miles. Step beyond those boundaries, and you're in another local authority area, like Hackney, Westminster or (across the bridges) Southwark. The CoL owns and administrates large pockets beyond its borders, such as Hampstead Heath and Epping Forest, but these are not considered to part of the City, per se. We would say that Epping Forest is in Essex (and partly in Greater London) rather than being in the City of London.
In addition to being a city, the City of London is also the UK's smallest ceremonial county — and by a long margin. The next smallest is Bristol, which is something like 42 sq miles. Rutland, often touted as the UK's smallest county, is 147 sq miles. (It is the smallest historic county, but is only fourth in modern administrative rankings.)
Winner: City of London is by far the smallest local authority and ceremonial county.
Finally, although it's irrelevant to our main question about size, it's interesting to consider which of our two cities is the most ancient. That one's easy. The City of London is one of the oldest extant settlements in the country, having been founded by the Romans sometime around 43 AD. When exactly it was regarded as a city is lost to history; its rights and privileges are said to extend to time immemorial. The City of London was given an official charter in 1067 by William I, but it was no doubt considered a city long before then.
St David's, meanwhile, is kind of a new kid on the block. It was regarded as a city from the 12th century, on account of having a cathedral. However, administrative changes in the Victorian era robbed it of that status. It was reappointed as a city in 1994, following an appeal during Elizabeth II's 40th coronation anniversary.
Winner: London is the older of the two cities
Summarise everything for me in one clause-laden sentence
The City of London is the smallest city and county by all measures in England, and the smallest city and county by local authority boundary in the UK, but is not the smallest in the UK by population or urban size.