Well, the saga continues! (caution anybody who's eating breakfast):
Despite flushing and draining for four days, and then draining for the next three (the wound had healed up too much to get in there to flush), the yuk just kept on coming!
So, we had the vet out again this morning. He made a new incision further down her jaw (no joy), then joined it up with the original (still no joy). Finally he stuck the blade in deeper at the site of the original incision, which resulted in a rather dramatic spurt of blood and yuk (I have learned to keep my face clear by now at least). I actually think we've been diligently draining surface gunk for the past few days, but leaving the actual abscess untouched (very hard to tell what's abscess and what's inflammation).
'Bonnie' has now been re-christened 'Scarface', but hopefully she'll turn the corner now. She's also had a decent jab of Betamox this time, which we're to continue with for the next few days. I'll call them again on Monday to report progress and decide what to do next.
Quite a learning experience this one......