Bertine, Waitrose do some really nice hot dogs.
They're in a pack of 4, and they're called Bavarian Frankfurters. I can't remember a brand name or anything, but they're in transparent packaging, with a rather plain-ish label. Sorry for my crap description, but I hope you find them. I think they're great, and quite often take them cold, for my work lunch, in Waitrose brioche hot dog rolls.