The gearlever gaitor is held on by a metal crimped clip. Unclip the base of the gaitor from the centre console and pull the gaitor up and over the gearknob and you will see what I mean. The clip can either be cut off or twisted side to side with pliers to loosen the tension. Once the tension is released the gear knob simply pulls off.
I bought a gaitor off Ebay and highly recommend this seller, tinyurl.com/yk5svmh , the quality is superb (proper leather as opposed to the standard PVC which cracks and tears easily) and is very easy to fit. You only get the leather gaitor and there is no plastic base mounting bracket. You just remove the staples which attach the old gaitor to the bracket and the new one has an elasticated base which just stretches over this; the top part of the gaitor is secured onto the gearlever knob using the existing top hat type clip.
To resecure the gearknob, I used a strong cable tie in place of the metal clip. A jubilee clip would also suffice.