Today I removed my damaged quarter window trim and took some pics of the clips before refitting the replacement. There are 5 clips along the top which are fused into the bonding behind the glass. There are 5 different clips along the bottom which can be removed. These bottom clips locate onto small body-mounted headed pegs and require firm pressure to click on.

I removed the Dorchester grey painted metal insert from my damaged trim and then refitted it so you can see how these clips engage into the ABS plastic. The top 5 clips have sprung thickness and engage within small rectangular slots. The bottom 5 clips are barbed gripper type and engage with a ‘blade’ shape in the plastic. The ends of the ‘blades’ tend to tear off during removal so it’s recommended to use plastic lever tools to carefully prise the trim off. Hope this helps someone in future!