There is absolutely nothing like someone criticising the British to bring the British together.
Remember just before the Olympics last year, when we were all still convinced it was going to be a total flop, and then US presidential candidate Mitt Romney came over, essentially said the same thing, and, well, we all went a little nuts?
Not even Boris Johnson getting stuck on a zip wire managed to unite the country so effectively. One wonders whether Boris suggested the wording himself: "Dear Mitt, if you could perhaps imply we haven't got it all quite together, and point out what a great job you did in Salt Lake City, I'm sure I can swing it for the PM to say he'd prefer you to win the election rather than that Obama guy."
One "It's hard to know just how well it will turn out" from Romney later, and everyone's convinced it'll be the greatest Games the world has ever known. Oh, and Johnson has become a national hero.
Fast forward a year and a bit, and with Cameron licking his wounds over his Syria Commons defeat, one of Vladimir Putin's senior aides steps in with a nicely timed insult, and we're lining up behind the PM to defend our glorious nation.
Yes, Russia, we might only be a "small island" but we have got a big character, and we really don't like foreign politicians putting us down.
Cameron made the most of the opportunity to reaffirm his credentials as a global leader, or at the very least whip up some support back home, by pointing out that the UK "invented most of the things worth inventing". That's a personal opinion that might or might not be true, depending on which side of the English Channel you happen to be living, but sounds like a slogan we should at least consider adopting for the country at large some time soon.
Sensing the need to ensure no own goal, Cameron made sure to include everyone in his rallying cry, insisting: "For the people who live in Northern Ireland, I should say we are not just an island we are a collection of islands. I don't want anyone in Shetland or Orkney to feel left out by this."
Of course, Cameron delivered his rebuke in the politest possible terms, a form of argument that is probably high up on that aforementioned list of excellent things we invented.
If the other members of the G20 haven't yet seen the viral hit that is a guide to British politeness, it's high time they did. In fact, it should probably become standard issue for everyone coming through passport control at Heathrow and Gatwick.
Not read it yet? Translations include, "With the greatest of respect", which actually means, "You are an idiot", but which foreigners think means, "He is listening to me". Then there's, "I only have a few minor comments", which foreigners think means, "He has found a few typos", but in fact means, "Please rewrite completely".
Any of those sound familiar?
Men might be from Mars and women from Venus. But we're from Great Britain, and that's a totally different planet (albeit quite a small one).