Ultraviolet was amazing, it proved that the UK CAN still do decent sci-fi (and coming just after Invasion: Earth, that was quite a relief).
However, they creully decided not to make s econd series not because of poor feedback but simply because they diodn;t want to. They made a full-length American version that I understand had a more soap-opera feel to it that I still have not seen; Idris Elba (Vaughn) was in it, but niot playing the same character.