The pollen filter was relatively clean, having been changed at the service last year. However, I have now fitted a new one.
As for the drain, the original tube in the bottom of the plenum area must have been removed by the Saab specialist when the car was in for service last year, because I cleaned it out when I first got the car, but there isn't one there now, so just a large hole to allow water to escape!!!
So it must be something else.......