World War II Sunglasses with Leather Protectors & Case

Here we have a pair of sunglasses with leather side eye leather protectors still in place.  The standard war issue case is stamped A (crown) M with the product number H.523315/41/C.I.C.  If anyone knows the history of these type of glasses I would love to know.  Similar appeared in the BBC Production "Rogue Heroes" about the SAS.