Further to my earlier post regarding a ground beetle I couldn't id (thanks to Linda and to Calderdale Wildlife for their comments), as well as posting on the blog for help I also contacted Mike Denton, an insect expert from Huddersfield, and he has now replied as follows:
"The beetle you found is indeed a Carabus species – but not nemoralis. It is a much rarer beast called Carabus nitens. The species is found in association with Heather, the colour of the wing-cases acting as camouflage. The species has the national status of Notable B as it only occurs in between 31 and 100 10km squares of the national grid. If you could gave me full locality details, along with date and a grid reference, I can then add it to my database. The species, many years ago, occurred about a mile up the road from where I live – the building of a caravan park put paid to that, however. Although I have seen many dead specimens from pitfall traps, I have never seen a live one!"