[Bluecortina]

I wonder if Central handled the kids programmes as an extension of them doing CITV (and Schools for that matter) in a similar way?

I think it's clearly a cockup by Granada pres, and there could be any number of reasons to have a circuit from Central available as an OS, although not many good ones for having it on the station output at that point!

Of course we will never know, but personally I think your explanation is probably close to the mark. 

In my view BT’s Manchester NSC correctly switched the local transmitter network from Knutsford to Granada at 9.25 who for some inexplicable reason had BAT3 on their Pres output. It was faded off pretty quickly (!) and importantly synchronously to black and thence to a local station ident. Framestores were in widespread use at that time and so BAT3 (or indeed any incoming circuit) being synchronous would be normal practice. A large company like Granada would have more than one incoming circuit and the fact that we see BAT3 rather than say LS3 is of no real significance - indeed the first programme might just as well be off a local Granada VT. But of course we will never know. 

As an aside I think the Knutsford centre had a small studio for inserts etc to the main TV-am programming. Years before TV-am took it over it was owned by the Distributive Industries Training Board as linked to by Stookie Bill in his post. I went on an RCA videotape maintenance course near Heathrow with a couple of chaps who worked there at the time - nice chaps, but I digress.