I think the article at http://www.metro.co.uk/news/article.html?in_article_id=68150&in_page_id=34 is a classic example of the media misrepresenting the facts.
Although the article headline is "Martial Archie becomes youngest black belt", there are a couple of quotes which make me wonder what they mean, exactly.
"he is the youngest of just 15 to have reached junior black belt"
"Because of his progress, he will skip through two grades in his new class, and will begin as a yellow stripe next year."
This seems to be similar to a system run by my club, where the kids rank in a separate system and get belts which are white with a coloured stripe through them. When they enter the adult class they go straight to yellow belt. We don't have any 6 year old black belts though!
Not to be unkind to the Metro (without it I'd actually have to look at the other people on London Underground... eugh), but it looks like they've latched on to "black belt" and tried to make a story out of it.
You beat me to it! I was going to post much the same that he isn't keeping the grade at all and it's only a junior one at that.
Still not to be unkind to Wiltshire lol but things are a tad shall we say 'slower' down there!