Hi all. My recently acquired MK3 estate has this little cap missing. Any photos I can find just show it blanked off but I was wondering if there is/was an option to have something fitted here, and therefore I may have more of a clue as to what I could search for to find a replacement? Might require a trip to a breakers yard but equally to spend a few £ on Ebay if I know what to search for. Any help much appreciated. 

At a guess, it'll be a headlight range adjustment for lower spec cars with halogen headlights.

 

It won't do anything on a car with xenon or LED headlights

Makes sense - thanks Langers