A leak in the tail-light lens is a remarkably common problem in a lot of vehicles. It’s even more likely if the vehicle has previously been in a crash and the tail-lights replaced by cheap imported units. You’ll spot a leak like this by condensation that will form inside the lens on a warm day.

Your mechanic is correct, too, if water gets into the light unit, it can then make it into the boot or hatchback area. From there, it will wet the carpet or boot-liner and potentially run down inside the rear quarter panel or the area where the spare tyre lives, where it will sit and start the process of rusting the car’s metal. If there’s a musty smell when you open the hatch, then you probably have a leak and it needs to be fixed pronto.

For a start, it’s never a good idea to drag a car anywhere with the wheels, hand-brake and steering locked. You can damage anything from the transmission, steering column, driveline and even ruin (flat-spot) the tyres.

If the clicking noise when you drive it wasn’t there before, then a mechanic would suspect that there’s been damage done to the front driveshafts. This would be consistent with the car being forcibly dragged along the ground. If you’re worried, have a mechanic check the car over and send the repair bill to your (now possibly ex-) housemate.

If it’s only the low beam light not working and we’re not talking about crash damage here, then you can change the globe at home. You’ll need a H7 replacement globe for the Astra, and the blown left-hand side globe can be removed by undoing a small, plastic access hatch inside the engine bay at the back of the light, squeezing the spring clip that holds the globe in its mount, and then removing the wiring plug. Then, you take the new globe and reverse the process, being careful not to touch the glass part of the globe as that can damage the new globe.

That all sounds pretty simple and it is if you’ve done it before, but it’s also a bit fiddly if you’re a first-timer. But before spending money at a workshop to have the globe changed, check out some of the bigger chain auto parts stores. Many of these have a free fitting service for things like wiper blades and globes.