That canal runs right past the front of Central Ordnance Depot Weedon which had massive quantities of small arms pass through its doors in the war. The brick buildings looks to be part of COD Weedon which is now a commercial storage facility with most of the original buildings intact. Why these Sten's ended up in the canal I don't know. Weedon would have had proper procedures for the destruction of small arms, which would have involved the metal ending up in a furnace. If the Sten's ended up being covered in algae on the bed of the canal this would have reduced the amount of oxidation and may have help preserve the metal, to a degree. The Airborne rear grips , if genuine (!) must be worth good money if they are in reasonable shape. No license required for these or the magazines in the U.K. Regards Alan