This gauge I know very little about.  One fellow vintage scuba diver advised me that he saw one just like it in use by the Australian Army Commandos however.  They used it in conjunction with an AVON CDBA rebreather.  This is an interesting choice for rebreather divers since the gauge goes down to 200 feet and the rebreather they used was an Oxygen variation suitable for 33 feet of depth.  Based on this and other information this gauge was likely made in the 50s.