The public highway is not normally the place to foster your love of a fellow human being (it's usually the place we grunt, grind and gesture at each other) but there are few moments in life as heart-warming as a complete stranger taking the time to warn you of a speed trap round the next bend.
It is a fleeting glimpse of driver camaraderie; a split-second confirmation that despite appearances we are, in fact, not alone on the road, but rather a full-time member of a British motoring community still capable of showing others care and consideration.
We'd place that brief flash of the headlights right up there with someone winding down a window to explain why you're stuck in a queue or even the concerned soul who stops to help after an accident.
It's so close to our hearts that we greeted the news of Michael Thompson's conviction for willfully obstructing a police officer with the kind of glum resignation we reserve for only the most idiotic and frustrating application of the nation's laws.
For those who missed the story, Mr Thompson was prosecuted by Grimsby magistrates for warning other motorists of a speed trap on the A46. The court rejected his argument that he was simply trying to help other drivers avoid an accident and demanded £440 in fines and costs.
The zeal with which the authorities are currently pursuing any and all manner of inconsequential infringements on the road is threatening to corrode the respect the motorist must hold for the rules and those that enforce them.
If the intention of a radar trap is simply to ensure that drivers slow down in residential areas or outside schools or hospitals then their presence on our streets is just. But if that purpose is qualified only by how many people the police successfully prosecute rather than a quantifiable reduction in traffic speed then they risk the resentment and distrust of each and every law-abiding taxpayer caught in their sights.
Mr Thompson did not encourage motorists to break the law after the speed trap; he had no more control over their behaviour than the police did once they'd passed the radar gun. All he did was suggest that they might want consider their speed in the next two hundred metres – fulfilling precisely the same role as the trap he was apparently obstructing.
Good luck to him. Had we been going the other way that day we would have flashed our thanks and driven on a little happier with a world where we can still count on the kindness of strangers.