Its a RHD car so it was probably somewhere the UK controlled at the time, or possible a German embassy staff car.
I have seen Mercedes vin plates from cars made just after that with swastika's stamped on them.
Mercedes keeps excellent records, because they are German. You can walk into a Mercedes dealer and threw the classic center probably still get just about every part on that car. Also you can send away with the vin and they will look it up and give you a history if you want. Like this guy did...
