I'd say this is probably due to our weird relationship with class. What is internationally thought of as the British accent is spoken by so few of us and is basically the reserve of the upper/political classes, so whenever somebody of the lower classes (the 99%!) hears talk of a British accent, they are immediately at pains to point out just how unrepresentative that accent is, but it's the one the world knows because of the BBC and our political classes.
So I guess by pointing this accent thing out, I'm marking myself as an 'everyman' and not part of the elite, however unconscious that was when I wrote it.
"it's the one the world knows because of the BBC and our political classes" - I should say it's the one we think the world only knows about.
Trying to dig myself out of a hole here...