My thanks to Gary Hancock for identifying this satchel and allowing a complete update.
When the L2 grenade was introduced it was a near-direct copy of the US M26 fragmentation grenade and could be attached to an adaptor and launched as a rifle grenade. this required a tail piece adaptor and a special cartridge:To carry these tail unit adaptors and cartridges a special satchel was issued in British service:The bag is made of the same cotton twill as .303 bandoliers and has a box lid secured by two copper staples, again like a bandolier:The inside of the bag is divided up into five spaces with an internal divider:These pockets each hold one of the tail units, vertically. The base of the bag is ‘D’ shaped and heavily padded:The inside of the bag has an ink stamping with an ordnance code, SV375A, a date of October 1966 and a manufacturer of C.B. & Co Ltd:This sort of rifle grenade was never hugely popular in British service and I suspect most examples of the satchel found today are like this one unissued. Again it is conjecture, but I would imagine the reason for the similarity in construction to cotton bandoliers is that it was expected the satchel would be thrown away when its contents were used up, again like the ammunition bandoliers of the era.