The surgeon rang. All is well. Ended up being a quadruple bypass (Dad will be happy, he doesn’t like to do things by halves, or thirds). He seemed to cope perfectly with the surgery and now it’s the critical 24-48 hours but the surgeon said she was very confident that all should progress well.
Mum’s over the moon, we’re all relieved.
Thanks to everyone who has commented or e-mailed, it really made a tense time a lot easier.