I thought about it. They have done a couple of free fixes on it for me a while back (once when it wasn't accepting charge and another time when I managed to pull the cable out of the lamp!)
They do have a section on their website about lamp units over five years old:
"This includes HID Mk 1 and Mk 2, Vision 1 LED Mk 1, Vision 1 LED Adventure Mk 1, Vision 2 LED Mk 1 and Mk 2, Vision 4 LED, District rear light Mk 1, R1, R4 Mk1.
These are not covered under warranty and we are no longer able to carry our any repair work due to spare parts being discontinued. PLEASE DO NOT SEND THEM BACK TO US.
If we receive any of these lamps, no work will be carried out and they will be sent back"