The windscreen. It’s not an annoyance, an inconvenience or in any way a hindrance. Being able to see where we’re going is a fundamental requirement for us mere mortals.

So why do so many drivers choose not to keep it clear? At this time of year you have floods of people with windscreens so dirty they’re opaque, but the thing that’s been really getting up my nose lately is sat-nav positioning.

If only I’d had a passenger who could have captured some pictures of the worst ones! I’ve seen navig-ation units suckered to the windscreen so directly in a driver’s line of sight that their owners were left hunched, peering through a narrow gap between the nav screen and the car’s instrument binnacle.

I’ve seen endless Garmins, TomToms, Navmans (Navmen?) and the like set just to the left of there, right in the centre of the windscreen. Don’t these people need to go around left-hand bends? If they do, they must have to do it more or less blind. Which is, er, a bit worrying.

A lot of these sat-nav screens are five or six inches across, and then the device’s thick frame sits outside of that. We’re talking about a serious piece of sight-obscuring electronics placed, apparently without a care in the world, right into an important line of sight.

But if that’s annoying because of its frequency, one instance I came across recently took the biscuit for sheer insanity. A young driver who I would dearly love to name and shame (if only I knew who they were) had stuck their full-size iPad to their windscreen, presumably using a mapping app to guide their way. Can it guide you around the parked cars and cyclists you can’t see, I wonder? Hmmm.

Is it just me who’s seen this? Is it some new kind of bizarre suicide cult? People who won’t part with their electronics for even a second are everywhere, but what kind of idiot thinks that eclipsing the road ahead with 10 inches of Google Maps is okay?

Even if common sense isn’t quite dying out yet, it’s a rarified atmo-sphere being breathed by fewer and fewer of those people in possession of a driving licence. The Highway Code states: “Windscreens and windows must be kept clean and clear of all obstructions.” Nobody’s saying the rule can’t be bent a little, but as for blocking your lines of sight? Insanity.