Yep - my point was that the accents were bad (i.e. not authentic) not that they were particularly strong or impenetrable (which I didn't think they were) I only ever used to put on subtitles (as closed captions are called over here) when I was on the phone. Now that almost everything is viewed on PVRs/DVRs (OTA and FTA satellite DVRs are very popular here) I just hit pause!
I guess I find it odd that audiences in the US would need subtitles for a UK drama - as I don't need subtitles for US dramas. However I guess us Brits, who grew up with a diet of US drama in the 70s and 80s, and the influence of Hollywood, mean that we are probably much more exposed to a wide variety of US accents, dialects and idioms. I also suspect that some US stuff is toned down a little bit to assist in US sales (and avoid alienating viewers in the wildly different markets across the US?)