I'm not sure what the exact status of Mink is now, but I believe the continued comeback/spread of the European Otter in the UK nowadays, is having some effect on the numbers of Mink, as Otters will kill Mink and their kits. Its a form of rough justice really, as when Mink first became established here they took over(partially) the niche vacated by the drastic decline of our Otters.
We still have a mink problem here in Essex Pertinax, last year a whole brood of swans was lost to them in one of my gardens, and I have seen a couple of mink run over this year, I also saw a dead pole cat too this year, not sure if it was a wild one, or a polecat ferret. sadly I couldn't stop to pick up the body.