Hi,
Two quick points:
1) "24" will almost always look better on Sky Digital BBC2, than Sky Digital BBC Choice. SImply down to the bandwidth Sky allocates to each channel. As BBC2 is a big mainstream channel, it will get more space to send picture and audio, than BBC Choice will.
2) It is very common for most end-credit announcements and voiceovers to be pre-recorded, and then played back by a timed computer, or for a button to be pushed to play the announcement by the tea-boy/girl. Sadly, a) if the computer mistimes, then the announcement airs early, and it can't easily be silenced, or b) depending on how technically competent the teaboy/girl is, he/she will have to time it correctly, to make sure the announcement doesn't clash with the program. Sadly, many voiceovers do clash, which - in my opinion - seems to imply technical incompetence on the station, and not just a once-off human error.
A better solution, would be to ban all voiceovers and adverts of any kind, until the end of a show!
Pooch