Today, while the police in
Stuttgart shows the coat of arms of Badem-Württhemberg, the police in
Hannover as part of the police of
Lower saxony still has that horse on the uniform.
So far, so good, but:
Police in Baden-Württhemberg was reorganisised about 1975, it was centralized, the city police of Stuttgart became police of Baden-Württhemberg with a new uniform.
Here i found a collectors website about police-patches. The city police had a horse on their patch too.
When i compare the stamp with the patches there, i think, Ron Wood is right