I agree that the timing of Butlins makes for a busy start to the year(!), but to be fair, I believe the regional date was changed. Of course that's their perogative but it smacks of the usual lack of communication in the upper echelons of our movement. (Sorry I said movement there which implies a group of people moving together which hardly describes brass banding at the moment).
Its a real shame as it deprives a good contest of bands from the North West - one of our strongest regions.
As for the date of Butlins itself - I imagine the camp is still open to hardy souls who want to holiday in Skegness in September. October (and September) would similarly clash with the finals, November clashes with Brass in Concert, the Wilkinson's contest and Leicester and the WMBBA contest (Leamington as was) December is a no-no for obvious reasons. So its difficult for them to find a date in their closed season that doesn't clash with already established events. Thinking about it though even the January date clashes with the RNCM weekend, plus the proximity of the NW regionals.
So while the thought of the East Coast in January hardly fills me with anticipation (weather wise I mean), its probably the only date available given the various other events in the calendar.
I personally wouldn't mind a return to the traditional early November date. When the CISWO contest was held in November it was always pretty well attended. Now that Pontins is no more, there is no major conflicting contests that would stop it being moved back. I know you highlighted a few local contests in or around the date, but again when Pontins was held at the end of October bands, especially in the north west, seemed to be able to manage them all.
That said i'm not sure the weather would be any better at that time of year!