Hello again,
sorry for answering with delay, but there is some life outside of the computer that keeps me busy.
I did some resaerch and must apologize for my mistake. It looks like the Geco mark has been stamped on the gun during WW2 era.
What confused me first is the fact that the gun is wearing the czech proof mark from Prag 1940 "40 over Lion with N", and everybody knows that czechia has been occupied by german troops in 1939 and from then on they took over the production sites and factories and produced their P Mod. 27. Keeping in mind that Germany needed as many guns as possible it was for me impossible to believe that in 1940 some pistols made it to the civilian market. So I thought that Geco import mark has been put on after WW2.
But I was wrong. It seems like some of the first production rate of CZ 27 pistols produced in czechia before the germans took over the factory made it to the civilian market even after Germany occupied the country. Maybe some of these pistols were already lying in the czech proof house in Prag and passed by the german military control, or in the beginning of WW2 the german army was not interested in these few guns that were already on the civilian market - many reasons are possible. It looks like the gun has then been imported into the German Reich by the Geco Company, which in that time was a big ammunition manufacturer, but also was doing some small arms business.
As I mentioned before, according to the german gun law, the company importing guns into Germany has to put their individual mark/symbol/name on the gun. This law applies just on companies, not on private persons. So Genschow & Co. put their trademark on the gun to fulfill the law requirements.
So again, sorry for my mistake, it looks like that particular CZ 27 is quite some rare item, I guess there were not many of them being produced maybe late 1939, or early 1940, going to the czech proof house in 1940 and then going on the civilian market for being imported to Germany. Make sure the gun will stay in collectors hands!
Best regards, Andy