Interesting; that's a naval signalling torch with an Air Ministry stores label attached.
RN = Admiralty Pattern 16001A.
RAF = 5A/2878 Torches, Electric, Type J.
The Army may well have also allocated it a stores code in the WB series, and if it survived into the 1950s it would have probably acquired a NATO stock number before being discontinued.
The carrying strap with filters (most likely Red, Green and neutral density for reducing the light output) is something I've not seen before.
Best regards,
Chris.