Beehive Bedlam was the best, but the one problem with Sky...
Used to drive me insane. I can't actually remember where (e.g. which channel) this took place. I think it was an overnight loop on 999?
Agree on it being Sky Channel 999, which used to be (maybe still is) the channel the box would default to after a powercut etc, which is probably why I remember seeing it? I *think* this loop was played 24/7 rather than just overnight for a good while - definitely recall seeing it in the middle of the day!
Channel 998 is the default, though it seems now for some reason to have recently started broadcasting in HD.