l can not find where it is coming from but it is making the car smell awful.

Swim towards the light.

Radoio aerial on the roof above the light abd roof panel. Needs a new aerial base and fit it up with a good dollop of car body sealer.

My Renault Laguna did it

My Peugeot 406 did it

My Clio did it

Must be the French rubbish

Good on you Fred - the man is right. l had this on my 406, my Cit C5 and Cit Xsara. Found out what it was when l had the xsara and discovered water running down the ariel lead which runs between the roof panel and roof lining. l resealed the base and that was that. The fault and reason was exactly the same on the other 2 cars mentioned..

look for rust spots above the windscreen trim or under it

Blocked drain channel for sun roof. Peal-back splash trim above the mudflap (2 screws) and remove the sludge from end of drain hose.
(check both sides of car)

check ariel seal known fault on these cars also check drainage holes for sun roof

Almost certainly the aerial base leaking.
Remove the light and undo the small retaining nut.
Clean and reseal the aerial base and rebuild, job done!!