I just thought, there is actually one thing in their favor if they lost - as a non-charitable organisation, they wouldn't be required to openly declare their finances, so they could shift money around much more easily, especially in light of the recent huge cash grab from the congregations. Maybe I'm giving them too much credit though.
Also, Half banana - you're maybe underestimating how much gift aid is worth to them. I don't think it's been mentioned on here, but gift aid these days isn't quite like it used to be where publishers had to make out a form and specifically declare that they wished their donations to be gift-aided (and very few publishers bothered to do it).
There was a new rule brought in over a year ago where they could say that any donation under £20 in the congregation box can be claimed back with gift aid. In the congregation here, even if there is more than £20 in the box, they will make out separate, individual receipts if it looks like the money could be from more than one person. (i.e. if it's two ten-pound notes rolled together, then that's obviously just from one person, but otherwise it gets divided into amounts smaller than £20 and put on separate receipts)