It works as it should do off my fused spur switch.
If possible, you could take some 3 core + earth from the fused switch to the light and thus have both a permanent live and a switched live wire at the light allowing the light to function as intended.
Wire colours:
Brown = Permanent live
Black (sleeved brown) = Switched live
Grey (Sleeved blue) = Neutral.
Earth sleeved bare copper = Earth