With reference to 'sharpness'. I believe that German dogs can still obtain certificates should they kill fox/feral cat when out in the field & this is suitably witnessed (it's not that long ago that they could be formally tested on this, so it is very much still in the blood). In which case this could be passed on to British bloodlines through German imports. My current dog has a German import Grandsire. She has been brought up with a cat & has shown little interest in them but she still managed to give me a scare towards the end of last season when she came upon a feral cat when we were out shooting.
Naj