Small opening/port on front grille?

Hello,
New on here. Thought I would ask about the front grille on a Mini Cooper s. my number plates got stolen recently and when I was examining the front, i noticed there is a small circular port towards the left hand side of the front grille. Does anyone know whether this should in fact have a cap to seal it off?

Sitting just behind that hole/port there is a metal pipe with a screw thread that looks like something should be screwed into it!?

Currently I've only got the bit of black grille/cap covering.
Just checking this is normal...

Thanks

Jeff