I recall that the machine came into - IIRC correctly - French hands very early
on it was passed to us and we had it LONG before the machine was taken from the
U-Boat.
Simple explanation. Yes, Ultra had been broken before the U-boat capture - however, Bletchley had been unable to break the German Navy codes: the Kriegsmarine's enigma had an extra wheel (four rather than the standard enigma's three). The capture of the U-boat's code books led to the discovery of the naval enigma settings for the next few months allowing the Allies to finally decode the naval code.
The RAF Digby Heritage Centre holds an example of a naval enigman machine should anyone wish to see one.