I was born in the 70s and grew up in a tiny rural village. There was, I think, only one black kid in my primary school. One day, someone pushed him over and called him "blackjack". The headmaster called an impromptu assembly. It involved the entire school, and took place outdoors. No doubt: this was unusual.

We stood in military rows in the playground. I must have been about six, so I can't remember the words he used, but the substance stuck. He spoke with eerie, measured anger. He'd fought in the second world war, he told us. Our village had a memorial commemorating friends of his who had died. Many were relatives of ours. These villagers gave their lives fighting a regime that looked down on anyone "different", that tried to blame others for any problem they could find; a bullying, racist regime called "the Nazis". Millions of people had died thanks to their bigotry and prejudice. And he told us that anyone who picked on anyone else because they were "different' wasn't merely insulting the object of their derision, but insulting the headmaster himself, and his dead friends, and our dead relatives, the ones on the war memorial. And if he heard of anyone - anyone - using racist language again, they'd immediately get the slipper.

Corporal punishment was still alive and well, see. The slipper was his nuclear bomb.

It was the first time I was explicitly told that racism was unpleasant and it was a lesson served with a side order of patriot fries. Or rather, chips. Our headmaster had fought for his country, and for tolerance, all at once. That's what I understood it meant to be truly "British": to be polite, and civil and fair of mind. (And to occasionally wallop schoolkids with slippers, admittedly, but we'll overlook that, OK? We've moved on.)

But according to the BNP, I'm wrong. Being British is actually about feeling aggressed, mistrustful, overlooked, isolated, powerless, and petrified of "losing my identity". Britishness incorporates a propensity to look around me with jealous eyes, fuming over imaginary sums of money being doled out to child-molesting asylum-seekers by corrupt PC politicians who've lost touch with the common man - a common man who, coincidentally, happens to be white.

They're wrong, obviously. None of these qualities has anything whatsoever to do with being British, but everything to do with ugly nationalist politics. And ugly nationalist politics are popular all over the world. Just like Pringles. Every country has its own tiny enclave of frightened, disenfranchised, misguided souls clinging to their national flag, claiming they're the REAL patriots, saying everyone's out to get them. It's an international weakness. For the BNP to claim to be more British than the other British parties is as nonsensical as your dad suddenly claiming to have invented the beard.

The other day, the BNP had a political broadcast on the box. I wasn't in my beloved homeland at the time, but I heard about it, via internet chuckles of derision. Fellow geeky types tweeting about the poor production values. I looked it up on YouTube. Sure enough, it was badly made. No surprise there. Extremist material of any kind always looks gaudy and cheap, like a bad pizza menu. Not because they can't afford decent computers - these days you can knock up a professional CD cover on a pay-as-you-go mobile - but because anyone who's good at graphic design is likely to be a thoughtful, inquisitive sort by nature. And thoughtful, inquisitive sorts tend to think fascism is a bit shit, to be honest. If the BNP really were the greatest British party, they'd have the greatest British designer working for them - Jonathan Ive, perhaps, the man who designed the iPod. But they don't. They've got someone who tries to stab your eyes out with primary colours.

But there's more to the advert's failure than its hideous use of colour schemes. Every aspect of it is bad. The framing is bad. The sound is bad. The script is bad. For all their talk about representing the Great British Worker, when it comes to promotional material, the BNP can't even represent the most basic British craftsmanship.

Nick Griffin's first line is "Don't turn it off!", which in terms of opening gambits is about as enticing as hearing someone shout "Try not to be sick!" immediately prior to intercourse. He goes on to claim that, "We're all angry about professional politicians with their snouts in the public trough." He's right, we are: so angry we're prepared to instantly forget all the occasions we've fiddled our own expenses, thereby enabling us to add a dash of undeserved self-righteousness to our existing justified anger.

But by referring to "professional politicians", Griffin is presumably suggesting we should elect amateurs instead. Maybe that's why the advert's so amateurish. Maybe that's why all the BNP representatives in the ad read their lines so clumsily, like DFS employees in a bank holiday sale commercial circa 1986, or recently revived chemical coma patients being forced to recite barcode numbers at gunpoint. It's deliberate incompetence. Don't vote for those nasty slick parties. Vote for a shoddy one! Never mind the extremism, feel the ineptitude.

Here's a fantasy. We - the decent British majority - spend years toiling in secret, creating a life-size replica of Britain in the middle of the Pacific. It's identical down to the tiniest blade of grass, or branch of Gregg's. And one night, while every member of the BNP is asleep, we whisk them via helicopter to this replica UK, this Backup Britain. Put them in replica beds in replica homes. Then we fly back home to watch the fun on CCTV.

For several weeks, they walk around, confused, but pleased. The weather's nice! More importantly, there are no black faces! Then the infrastructure breaks down and they start to starve, and there's no one to blame but themselves. And then someone with GPS on their phone works out what's happened, realises they've all become immigrants in their own land. Half of them go mad and start attacking each other. The rest desperately apply for asylum in Britain. The real Britain. The decent, tolerant Britain. The country you can be proud of.