First step is to remove the sideskirts as shown here.

The 451 also requires the tailgate to be removed before the rear panels can be removed due to interference of the tailgate when in place. The guide for removing the boot panel is here and the tailgate removal is here.

Unclip the 2 plastic tabs from the under rear valence.

Remove the 2 securing T25 Torx screws on each side in the trid where the skirt covers.

Remove the 2 T25 screw located in the lower rear valance.

Remove the 2 T25 screws securing the panel next to the rear lights.

Remove the single T25 torx screw from the middle of the centre panel.

From the bottom edge of the side of the rear panel, carefully pull the panel out. It is simply held in place by small plastic clips which clip into a mount on the trid.

There are small metal clips which hold the light surrounds, but again, gently pull this away from the car and they should free without a problem.

Remember on the offside you need to disconnect the fuel door actuator and pull the rubber seal off the filler neck.

As you pull the rear away from the car you can now disconnect the rear lights, your other option is to disconnect them through the service hatches inside the boot.

The panel is now free to be removed.