The airbox is located within the engine bay in the back left corner.
In order to remove the lid off the airbox, the induction pipe needs to be removed. Use a flat blade screwdriver to loosen the jubilee clip. Loosen it enough to pull the clip along the pipe.
Pull the pipe off the end of the airbox. This is a little tricky as there is not much room.
Free all three clips from the front face of the airbox. One is located under the induction pipe outlet.
With a bit of manipulation, the lid will lift up off the airbox and come free.
The air filter simply sits within the airbox.
Lift out the old filter.
Use a vacuum cleaner to suck out any leaves and debris from the airbox. Take care not to get anything down the induction pipe that was disconnected in the first step. Replace the filter when done.
If you try to correctly refit the airbox lid, it will be very difficult to get the induction pipe back on. Therefore, push the lid as far back into the engine bay as you can. You will now be able to get the induction pipe back on.
Pull the lid as far forward as possible in order to clip the back of the lid onto the airbox.
Fasten the clips.
Finally, tighten the jubilee clip.