Ed Balls' performances on Strictly Come Dancing shed more light upon politics than is generally appreciated.

What I mean is that Balls the politician was presented as an unsympathetic figure. "Bruiser" and "bully" were common descriptions, and his coining the phrase "post-neoclassical endogenous growth theory" gave the impression of being a pointy-headed technocrat. He embodied the Oxbridge elite that is supposedly out of touch with the common man.

And yet on Strictly his performances have been "a rare delight to brighten our weeks". He's charming, popular and funny: we've been laughing with him, not just at him.

Which poses the question: how can there be such a massive difference between Balls the politician and Balls the dancer?

It's tempting to blame the media. After all, the same journalists who painted so unsympathetic portrait of Balls also made a public schoolboy who doesn't listen to music or watch TV into a man of the people, and a serial liar and friend of a criminal into a loveable buffoon. The BBC, of course, has been complicit in this misrepresentation, and remains so: just listen to how John Humphrys usually aggressive interview technique deserted him this morning (2'09" in) when faced with a Trump crony.

But perhaps there's something else. Balls the politician made a terrible mistake. It's the same error Ed Miliband is making when he calls upon the left to "rebuild with deep thinking". This mistake is to take politics seriously.

Doing so has two costs. One is that being serious commits you to some principles and a vague commitment to the truth as you perceive it. This puts you out of touch with ordinary voters with your truth conflicts with theirs, and makes you inflexible. By contrast, the Tories lack of interest in ideas allowed them to shift from being a party of the metropolitan elite to appearing as a sort of Ukip-lite. And it enabled Trump to tell his voters what they wanted to hear, regardless of whether he can or will enact his promises.

The other cost is that it means you come across badly on TV. If you prepare well for interviews and try to make serious points, you'll look humourless and out of touch. The Johnson cheeky chappie approach works better.

Political success is achieved today by treating public life as a game, as a jolly jape. Taking it seriously destines you to failure.

Again, the BBC is complicit in this. It invited Marine Le Pen onto the Marr show not out of a deep interest in French politics but because it knows that fascism sells. It booked Le Pen rather than Alain Juppe (the favourite to be next president) because it thought it would be "good TV". And it rewards politicians like Johnson who play along with this aim.

The idea that the BBC's politics output is high-minded is nonsense. It is part of the entertainment business just like Strictly is. The difference is that Strictly is good entertainment.