Why, I asked myself was I getting 'Congregational Studies in the Uk' every time I referenced said book directly from Endnote?  Yes, it was 'UK' in the data entry table but, aha, Chicago 15th A does not like the UK or even OK or indeed anything much except USA.  Chicago 15th B likes UK, but does other things I, or my supervisors, don't like.  Oh, I love it, not, but it is quicker, and more accurate, than manually typing in all the references, which as I have 158 at the last count, is definitely a good thing...

At least I have now found out how to make it reference doctoral theses correctly from said format, but there's still some tweaking needed here and there.

Ah well, into the final stages of editing now...

UPDATE

OK, so another ten minutes of messing around and I discover in the 'preferences' menu that I can set UK as something for it not to alter the case of, have found out to do multiple citations prperly and half a dozen other useful things.... Grrr.