In 1994, when CBBC was on BBC2 because of Wimbledon, some CBBC shows got into the BBC2 Top Ten, the likes of Blue Peter and Byker Grove, which had about 2.3 million viewers (albeit this was at 5.30, rather than the usual 5pm slot). I'm not sure about the audience it would have got on BBC1, about the same or maybe more as the competition from BBC2 would have been weaker. BBC2 didn't really try hard at teatime until late 1994, when Ready Steady Cook started, so the only competition was other kiRAB shows on ITV and Countdown, which was almost always Channel Four's biggest show. In the eighties they would get about six million viewers.
That said, despite its low ratings, those who watch Blue Peter are very loyal. One of their recent competitions got 10,000 entries which, given only about 200,000 watch it some days, is a masive response, most shows would kill for 5% of their audience to write in. The appeal's another one, they've already had over 150,000 donations.
Yes, and the thing about moving Corrie around like this is that it may make sense from a scheduling perspective, but it makes no sense for the viewers. Moving it to Thursday was sold as being because of the football, but ITV can't move it Tuesday and say "We're moving it because Tuesdays aren't rating". That'll just confuse and annoy everyone.
The reason Corrie is declining is entirely down to these scheduling shuffles, and adding an 8pm showing to 7.30 and 8.30 showings just makes it more confusing. It's already stupid enough that after saying it wouldn't be on Wednesdays and Sundays anymore, they shove it on odd Wednesdays and Sundays. If the normal slot is unavailable, they'd be better off just not showing it than rescheduling it for yet another slot. It does nothing for viewer loyalty. Never mind how many are commissioned, it'll all even out in the long run.
I've said this before but Emmerdale should be at 7pm Monday to Friday, with an hour-long episode on Wednesday when there's room. That would mean everyone knows exactly when Emmerdale's on, and it would lose the pointless sixth episode which is only there because they can make six a week, it's of no benefit to the quality of the programme.
Also, if Corrie was ever to move from Monday at 7.30 that would be hideous because it's been there since 1961, which must be the most established slot in the history of television.