Hi Steilgr the Royal Marines were the last to use the 3.7 in British service at Walcheren in November ,1944 the story goes a German sniper was holding up the advance into Flushing ,the gunners couldnt get a clear shot without them been in the line of fire ,so they dismantled the gun [ i think the gun was originally design to be broke into 5 ? pieses of 200lb a piece to be put on mules] took the pieces into a house , rebuilt it in the front bedroom and dealt with the sniper ,after 8 rounds the gun was hanging through the floor
I think the Pakistani still used them postwar .My old doctor has one ,which he holds on a firearms licence and regularly fires ,hes featured in the Sept /OCT 2004 issue of the Armourer ,Dave