Wow, thank you all very much for your responses (and apologies for my delayed acknowledgment as I had no internet access until now).
I doubt it was a DH Comet as she recalls the engines being radials with propellers (and always breaking down). The plane had arrived in Athens with Germanic speaking people en-route of which my mother recalls being either Austrian or Dutch. It could have been a charter, the plane was mostly full of young single women and there were a small number of families with children onboard - all heading to Australia. Apparently the plane stopped at Darwin then flew direct to Melbourne.
Thank you, CT.