The actual caliber in metric was 76.2 mm so it raises the question of the "7,5 cm" designation. A "beute" designation, "7,62 cm Flak Mounting (e)", is seen in a German document posted by Jos in 2009. See here:Schorschl wrote: [...]
It's a destroyed British Ordnance Q.F. 3 inch, 20 cwt. Some of these guns were captured by the Germans during operation "Dynamo" and later used under designation 7,5 cm Flak Vickers (e).
Greetings,
Schorschl
http://forum.axishistory.com/viewtopic. ... 0&t=155357
For the same battery of Callantsoog in the Netherlands, Rudi Rolf writes "7,62 K261(e)" in its book "Der Atlantikwall".
Emmanuel