Not what I planned to do today...

Call from bathroom this morning, "Come and see this".  Went in to find a big ugly brown slug, the size of a fat cigar, sliming it's way across the unit.  Yerrakk!!!!!   I hate slugs.  

She added, "Not only that but the extractor fan has gone off".

Never rains but it pours.  I took the cover off the fan unit and found the fried remains of another giant snail, pulled the motor unit out and there was a bird's nest behind it - and the unit was hot to the touch.  Bugger.

Seems the birds have found how to lift a vent flap and get inside to nest. In the process they've pulled the liner away from the extractor motor.  This allows snails in the cavity wall to get into the house.  Who'd have thought!  It's all dismantled now, will rebuild it tomorrow and see what happens.  Fingers crossed.