In reply to Fawksey:
i've got
a pair of m-frame oakleys with iridium lens and spare clear and yellow lens
a pair of bloc sunglasses from tkmaxx for "casual" wear (ok, ok, posing)
a pair of tesco £3 POS glasses that sit in the car incase i get caught out
probably the blocs would work under a motorbike helmet but tkmaxx have loads of sunglasses in most shops