There's a Torx bolt on the outside, plus the plastic wing not on the inside. It's then just a case of pulling. There are two spring clips on each rear cluster, one at the top and another at the bottom. They are located on the outer edge, nearest the wing not the boot hatch, which makes them hard to prise out. I just ended up getting fingernails under the side of the lamp unit and giving it some GBH then it started to come free. Then it' simply a case of working each out in turn.