Rain water in the back, on drivers side?

[Jade.c]

When I open the boot, it’s got a few drops of rain water on the right hand side in this little hole bit by the light, but I can’t work out where from..... I can’t see how any rain water can be getting in there! When I move the seat down, where it dips in, is also a bit wet, and then goes to the floor. Along the edge of the boot, right along the right hand side is wet!

I had the rear vents resealed a year ago, no water is in the spare wheel area, that’s dry? 

even my pushchair in the boot has now gone mouldy because it’s damp!! I poured a jug of water over the lights and looked underneath but couldn’t see any water dripping in so I’m unsure? 
 

can anyone help advise on what to do? I know rear vents to be resealed is common but I only had it done a year ago!!! 
 

thank you! 
 

It is a 12 plate mk3 focus. 

[F0CUE]

Pull off the plastic inside the top of the tailgate behind the spoiler they should pop off and see if the water has leaked through there. 

[Janner7859]

Pouring water on the lights may not be enough, you might have to use a hose pipe on them to get them to leak. I have a leak in the same place, and I often see drops of water running down the carpet under the back light area on the drivers side. I know for a fact that mine leaks on the screws that secure the light. As Focue says, check the rear spoiler as well.