I've got a theory and it's one that some of you won't like – but hear me out.

It is this: Driving at 10mph under the speed limit can actually be more dangerous than driving 10mph over it.

Sound ridiculous? Perhaps. But over the past few days I've seen more evidence to support my theory than rubbish it.

The one that really inspired me to put fingers to keyboard was on Sunday (now there's a surprise). Well-sighted country road, no pedestrians, no pavements, good road surface, good lighting. And it wasn't raining. Yet one driver steadfastly refused to top 30mph in a 40mph zone.

In fact it got so bad that even the slight whiff of an incline and he dropped to closer to 25mph.
I was five cars back in a queue of at least 15 other motorists. Snaking along behind him was all well and good – there was no real danger there – but where the real problem resided was with the other motorists.

A frustrated driver isn't a safe driver and there's nothing more frustrating than following someone that refuses to do anywhere close to the speed limit.

My point was very nearly proved. A Mercedes driver stuck behind Mr Go Slow was evidently getting more and more irate. Drifting across the centre of the road whenever he could peering round for a gap to overtake, it was clear he wasn't happy. It went on like this for five minutes, and then he went for it – narrowly missing an oncoming car in the process.

Now I'm not for one minute defending that Mercedes driver. What he did was clearly dangerous and he should, like the rest of us, have waited patiently behind the dawdling driver. No matter how infuriating it was.

However, my point is this – if you want to drive at 10mph under the speed limit, that's fine, but would it hurt to have some consideration for those behind you. Why not pull in and let those who are in a bit more of a hurry than you are get past?

If you haven't spotted there's a huge queue of traffic backed up behind you then your observational skills quite clearly need some polishing. And for a driver, poor observational skills is a bit of a problem.

Driving is all about courtesy – letting others in, letting others out. Our road network only works if we all realise there are other people on the roads wanting to get somewhere too. Bunching up a queue of cars behind you is inconsiderate and that frustration you're causing in other motorists is ultimately dangerous.

More dangerous, I'd propose, than those normally law abiding drivers who drift a few mph over the speed limit on a clear, three-lane motorway every now and again...

James Baggott is editor of Autoblog. Agree or disagree with his views? Let him know what you think by posting your comments below.