Many thanks for this. I did eventually get through to BA via the Australian number. They told me I had to call the UK baggage claims number, which I had already done. The latter simply gave recorded messages - i.e. nowhere to actually get a report number. And you can't make a claim online until you get a report number. So in short... I've been going in absolute, slightly comical circles. Hopefully K2 may be able to help.

Appreciate you taking the time to reply!