Honestly, it wouldn't even be that much. It would be a trivia question.

Even now the American revolution is kind of a non-event to the British. It is of less interest to them than the French revolution, which led to the Napoleonic wars and ultimately the rather drastic reshaping of European nations. George III is the villain in the American version of the story, but he's mostly known in the UK for his long, sad descent into madness.

They had their own Civil War in the 17th century, and even that tends to be glossed over in British history classes. They've just got so much more history than Americans do that it's just unfathomable. They don't really spare a lot of thought for the successful revolution, and an unsuccessful one would have been a footnote.