I assumed that the LEDs had failed but after a bit of experimenting I found that the tiny little connector in the wire feed had failed. It's the connector that is near the hinge end of the boot lid. It seems to get pulled when the boot is opened and I presume it just goes bad over time.
I replaced this connector and bingo - working spoiler lights.
Simple but I just thought I'd give a heads-up if anybody else has this problem.
Levi
