Having a look under the bonnet I noticed the two areas in the pictures, next to the suspension turrets. It seems strange to me that road debris should find its way up there, and also concerning as it's rather a good place for corrosion to start as a result. Has anyone else noticed this problem, and is there an easy solution?

Dirt gets everywhere!

This is spraying directly from the road wheels though, it seems. I'm thinking there's a venturi effect drawing it up through that tunnel. Not a good design feature.

Get it cleaned quick, it's making me feel uneasy

I'd be inclined to try to wedge the gap with a cloth of some kind to stop it making its way up, I've done this near the washer bottle on my MK6.

Good tip that

the only problem with blocking any hole is the water will have to find another place to go, the dirt will only be forced up there with big puddles and it has to go somewhere, i had mine without the arch liner in there for a few weeks and all the dirt went everywhere

Haven't dared look at that area since I posted this. With the rain and mud on our country lanes it's most likely got plants growing on each side now. Must get my pressure washer fixed, then give it a good hosedown.