What a pickle we are in. And no, I don’t mean Brexit.

Thirty years after the introduction of the national curriculum that was meant to provide a broad and balanced entitlement for every pupil, we seem to have ended up with a narrower, unenviable focus on just a couple of subjects. That surely wasn’t what was intended.

Whatever you might think about the result of the project, the principle behind a national curriculum seems fair to me: a common core that every pupil can benefit from, with room around the edges for schools to add their own local angle. Just common sense really, so how have we ended up in this mess?

A one-word answer covers most of it: accountability.

Don’t imagine for a moment that I think we shouldn’t have any accountability; far from it. But we do need intelligent accountability. A system that recognises the risks of perverse incentives, and does its best to minimise them. But we don’t have that. I guess the opposite of intelligent accountability would be dumb accountability, and that phrase seems to sum up the system pretty well.

Dumb accountability is fine as long as it’s part of a broader system with intelligence. We’ve got used to working with dumb systems, and we rely on intelligent - often human - intervention to temper the issues. We’re used to hearing “unexpected item in the bagging area” and waiting for an assistant to intervene. We understand that SatNavs can’t always tell the difference between a B-road and a bridleway, and so we haven’t quite yet given over control of our vehicles. Just this week, I stood at a platform where the automated screen told me my train doors were about to close - no train stood at the platform.

Intelligence required

Dumb systems are fine within an intelligent framework. But we don’t yet have that for school accountability. Our high-stakes, knee-jerk reaction system would be the equivalent of the ‘unexpected item’ message being replaced with automated arrest and charging with theft. Sure, you’d have your chance to argue your innocence, but, funnily enough, people probably wouldn’t stand for that. And if we all relied on the automated screens at train stations, we’d end up with a lot of people leaping onto the tracks in an effort to catch the non-existent train.

We can’t rely on dumb systems to do all the work for us.

That’s why I’ve been so pleased to join the accountability commission at the NAHT to find a better system for school accountability. It’s not the school leaders and teachers don’t want accountability; to be honest, I think most would actually be pretty disconcerted by that.

It’s not even the case that schools want rid of tests, by and large. Usually when people rally against testing in school, it’s the knock-on effects that they’re concerned about: the narrowing curriculum; the excessive focus on a small data set; the punitive accountability when graphs go downwards.

We’ve seen some positive moves in recent years. Ofsted has begun to take a much more intelligent approach to data, among other things, and inspection teams seem more willing to spend time unpicking the stories behind the data rather than simply making judgements based on numbers. Even the mysterious regional schools commissioners seem to taken a slightly less heavy-handed approach more recently.

But we’ve had enough tinkering around the edges. It’s well past the time where we need to look closely at the implications of the current accountability framework and decide what it is we really want from the system - and then maybe we can design something intelligent that fits the bill.

Michael Tidd is headteacher at Medmerry Primary School in West Sussex. He tweets as @MichaelT1979