Liquor is just one thing that helped fuel revolutionary America 250 years ago. People joining the UK events say they've enjoyed learning about the extent of the cultural crossover - not just because the US's big birthday is a milestone that resonates globally, but because it's also taught them things about their own part of the world.

Back in the City of London, participants on Mark Grant's tour say the deep-dive into American history has also had the effect of showing them a side of their city they never knew.

"It took me to a few alleys I'd never been to," says Peter Tidmarsh, a local. "I'm just amazed."

Not for nothing has Grant been a contestant 13 times on the BBC's Mastermind game show, thanks in part to his prolific knowledge of the UK capital. Blue plaques, historic pubs, and even the site of an church that was moved brick-by-brick to Missouri - all these sites feature on his tour.

For Grant, the Square Mile is its own character in the American story, and it offers an illuminating window into how a young US might have looked at a turning point in history. "The cities [in the UK and the US] would have been the same, and so this is kind of the foundation of it all," he reckons.

An Australian by birth, Grant acknowledges that he's neutral on the question of which side was responsible for the infamous 18th Century breakup. Britons on the tour, meanwhile, insist they're not taking sides either - they've just come along to learn something.

"Well, there's some regret," jokes Tim Parry from Essex. "But I think I think we got over it."

"I think 250 years is long enough," adds Tidmarsh.