A fair amount of content on BBC America is SD, but widescreen. The Brits were ahead of us on widescreen for TV since the late mid to late 1990's. The most recent content from BBC is in HD, but almost all the content, even the most recent, from other sources such as Channel 4, ITV, etc. (BBC America airs shows that air on rival UK channels), are in SD (shot in SD to this day), but widescreen.
I believe BBC World News is still in provided only in SD, but sent out widescreen. I think BBC has been considering BBC World for HD, but they (UK) are behind us in the whole transition to HD with even very few titles on Blu-ray, and most of those are BBC productions. I think even the latest Doc Martin series 5 that was first aired just months ago is still shot in SD because the BBC has the $$$ and resources to shoot in HD, but not ITV on which Doc Martin airs in the UK. All of The Inbetweeners (a Channel 4 show) were all shot SD. Sad.
However The Inbetweeners Movie was a theatrical release and is offered in Blu-ray, but all the TV episodes are forever SD.
I am not aware of any TV channels in the UK other than BBC that currently air programming in HD, and that is ONLY on the ONE HD channel the BBC airs and programs for which it doesn't have a lot of content, but it the HD content is slowly growing. Thankfully, Psychoville was BBC and we can enjoy that show in HD and Blu-ray.