Not sure as to whether anyone out there has suffered this problem, but I've
got the cure.
It manifests itself as a damp musty smell when just using the blower but
seems to disappear when starting the aircon.
The smell is caused by stagnant moisture in the system after using the
aircon in humid weather.
The cure is as follows:
Remove the cover from the pollen filter, and remove the filter. Next place
some cloths over the internal air vents and switch on the blower to full
speed. Then from outside the car spray Dettol disinfectant in aerosol form
into the system from where the pollen filter was removed. This will kill the
mould spores and any resident bacteria in the system. I used almost half a
can which completely cured the problem. This product can be obtained from
Asda and retails at around £1.79 per can. Well worth the money. Finally
remove the cloths from the interior, refit the pollen filter and cover.