The bridge has parted company from the belly again!
I had re-glued it with Araldite, and I thought this would be sufficient. Everything else is finished on the lute (frets all done, including the ebony ones of the body), so I strung it up again and tuned it to pitch. It was OK for a few minutes and then there was an ominous creaking followed by the familiar 'bang'. This time part of the bridge (the scroll at the end) did break, but this is a simple fix.
Maybe my glue joint wasn't good enough, or maybe the tension (i.e. my choice of strings) is too great. I am going with the first option, and so I will try again with Araldite - unless anyone out there has any better suggestions! .