Just back from local garage. The mechanic had already removed the trim around the ducting and a/c unit so that I could see where the water was coming from.There is a sturdy bracket that supports the ducting assembly on the drivers side. When he loosened the bolts on this bracket the whole assembly which was under strain moved down quite a bit on the drivers side. This had the effect of levelling out the black plastic tray that collects the condensate and taking the strain off the pipe that drains the condensate. He ran the a/c and water came through the drain pipe to the outside for the first time. He left me with the trim still removed to see what happens. The only difficulty is that the temperature has dropped now and even with the A/c set at the lowest temp 16C it is unlikely to produce much water until the weather improves. Even so no evidence of any more leaks. Seems to have solved the problem but I will update you if not.