Checked again tonight and there was hardly anything on the bottom of the engine so hopefully it is just the aircon. The car is a 59 plate with 25k on the clock so there is a little grime on the underneath of the engine bay. Even so i would not expect condensate to leave marks on the drive when it has dried.
Snoopy - I had a look at your photo. Is that taken from the underneath of the car looking up? (is that the right hand drive shaft?).
If this was my mk2 16v i'd have no problem seeing where the leak is coming from - the mk6 engine bay is crammed full!
