The cabin pollen filter is accessed from the engine bay, behind the cover circled by the faint yellow line.
Remove the engine cover by pulling upwards, it clips off.
Turn the clips slightly anti-clockwise, don't drop cover behind engine like I did.
Note the two clips moved rotated slightly.
Behind the cover is the shiney black plastic on the front of the filter.
The two lugs need to be squeezed & pulled to release filter - withdraw from engine bay, hey - my thumb looks weird!
Here it is slightly withdrawn.
Old and new.
Here's the hole left behind.
Fit new filter, push in until it clicks into place.
Refit cover, turning clips clockwise.
Refit engine cover & job done.