Bofors 40mm/L60 anti-arcraft autocannon with Stiffkey sights in Crete? Possible explanations?

This is a picture (click to enlarge) of the Bofors 40mm/L60 anti-aircraft autocannon mounted as a monument by the entrance of the German Soldiers' Cemetery (Deutscher Soldatenfriedhof) in Maleme, near Chania, Crete.

I did not consider it necessary at the time to take more detailed pictures, since I thought it was obvious that it was one of the several anti-aircraft guns of the British and Dominion forces that defended the Island of Crete ("Creforce") before it fell to German hands after the unexpected success of the daring and costly paratrooper operation Codename : Mercury (Unternehmen: Merkur).

When I got down to identify its exact type however I saw that it has been modified with the Stiffkey sights, the trapeze aiming aid that according to Wikipidia was sent out to British and Dominion in 1943. Crete was lost by the beginning of June 1941.

Assuming that these are indeed the Stiffkey sights and that the sights were introduced in 1943, then this gun was not a gun of the Creforce! How did it get to Crete? Imported as a trophy? Souvenir? Too bulky... Captured in Afrika and sent to the Axis garrison of Crete? All scenarios are improbable.

Puzzling... Any suggestion or comment would be helpful and more than welcome.


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