The pollen filter on a focus is situated under the grille panel at the bottom of the windscreen on the passenger side of the car.
First thing to do is remove the single screw, then carefully prize it free of its clips and remove the grille.
It is hard to see through this photo but the filter that was in there was caked in leaves and crap. The new one is white but the old one was grey when it was new, so the colour change is not a sign of age / condition.
Next job it to see how the Ford mod kit works. Ford didn't give me any instructions so luckily it was more than obvious. As it happens, my car must have had this kit fitted already, because as you can see, the clips are already in place:
At this point I recall that when I had a leak coming through on the drivers side, I had removed the other grille to see if I could find the cause of the leak. I remember the clips on that side were past their best, so decide to replace the passenger side clips with the new ones, and use the old ones for the drivers side. This meant removing the windscreen wipers which can be a tough job. The shaft they screw onto is conical so they can be a right bitch to shift.
Mine came off without much hassle this time, but remember to store them in such a way that it is obvious which one is which! Here you can see the conical spindle they are bolted onto.
Once I'd replaced the clips on the drivers side and replaced the grille, I could concentrate on the seal that was part of the mod kit. It seemed pretty obvious that it should go between the windscreen and the grille edge. Unlike the clips, this had not already been done but there was a line of silicon sealant on the windscreen! So I had to scrape this off first:
Then I applied the sealing strip to the grille and replaced it and the windscreen wipers.
Sorted! The pollen filter only needs changing every 20,000 miles according to my Haynes manual; I'd be surprised if mine had been changed in that time!