Unidentified WW2 Era Pistol Magazine. British or German??

An unidentified pistol magazine, this mag came in a German Radom pistol holster so could be German but the holster had been liberated by a serving British officer and then used in Libya in the early post war years so could also be British, all depends whether he had kept the German pistol that had originaly been in it or replaced it with the British equivalent?  Anyway it is in pretty much perfect condition and the cross section is of a pretty distinctive shape with the front edge being rounded so someone out there will know. It is just under 4 inches in length and is in excellent working condition.

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