Actually a good portion of BBCA is real HD. While the Brits are a bit behind us (for once) in HD content, things are gaining momentum as shows such as Doctor Who, Top Gear--most of BBCA's prime-time schedule is in true HD as they were produced so in the UK, but not necessarily aired in the UK domestically in Hi-Def. Unfortunately, BBCA still airs a lot of old standard def that looks it, but still improved from the SD BBCA Dish channel.
I'm unaware of any SD wide-screen programming on BBCA that has be "upconverted". I am aware of UK wide-screen programming still in Standard Def, but airing on BBCA HD. The effect is something like one would expect if it were "upconverted." It's just that almost any SD is going to look a lot better than it does on the standard def channel.
The sad part is that, the last I checked, BBC World News service was produced in wide-screen (at least for a number of years), but BBCA HD seems to zoom in and present it in a 4:3 aspect ratio. This is really unfortunate. BBCA used to air it in wide screen but zoomed with very thin black bars at top some time in the past (the UK wide-screen is a bit different from US wide-screen). I've also seen a few shows on BBCA HD that I know were produced in wide screen, but air on BBCA HD in an ugly forced 4:3 aspect ratio.