I did a search and didn't see this, so I'm posting this note in the hope it's helpful.
I've received the AGM docs from Liverpool Victoria, and they say they are moving from 0870 to 0845. Great, I thought, but that's not good enough (... rant rant, you know the thing, rant rant...).
Anyway, I've taken a little more trouble to read the doc and it says the following:
0845 costs per min:
Daytime 3p
Evening 1p
Weekend 0.5p
So my ranting (to myself) was in vain. These sound like extremely good value. It doesn't say when Evening starts, but I would assume after 19:00.
Anyway, I hope others find this useful!