This rather unusual-looking machine is the new Vauxhall Insignia estate, which made its public debut at the recent Paris show.I had to take a step back when its huge clamshell tailgate automatically opened to reveal a pair of secondary rear light clusters hidden in the boot lining.

But this unusual layout prompted a piece of well buried piece of trivia to come to mind. There’s an obscure EU regulation that requires all of a car’s lights to be visible, even when all the doors and lids are open.

This law is the reason many estates have stacked tail lights, wrapped around the corners of the body and why the old Freelander and Discovery (which had side-hinged tailgates) had the brake and tail lights mounted in the rear bumper.

Further back in time, it's part of the reason front-hinged bonnets, such as those on the old 3-series and 5-series BMWs, were killed off.

At least one car maker has been caught out by the regulations. A few years ago I recommended the Toyota RAV4 to two buyers. They both went to the dealer and rejected the car for the same reason. The rear tailgate wouldn’t open fully.

This didn’t make any sense until I realized the Toyota was forced to fit a special EU-market check strap to the side-hinged rear door, preventing it from opening fully and obscuring one of the rear lights… Another thing struck me about the Insignia too. This estate was clearly conceived in the boom times. In these post-credit-crunch days, there’s no way a car would be passed for production with two pairs of rear light clusters.