Well, that's sorted! (see yesterday's blog Lost Touch)
I worked out which church Don and Betty were likely to have attended, and got in touch with the minister. She didn't know them, but the organist did as Betty had been a member of his choir, and through church membership lists they were able to give me Betty's sister Nina's phone number.
This evening (their tomorrow morning) Pa phoned her, and she gave him not only David's and John's phone numbers, but also the welcome news that Don is not dead but just a rubbish correspondent. To be fair, he is not in the best of health and is now living in sheltered accomodation.
Because I was looking for these cousins I visited the Friends Reunited website which I have not looked at for a long time, and found that two people from primary school had left messages for me in January. I got in touch with both of them. Alan, who is by coincidence involved with a choir as its accompanist, sent me a lovely newsy email, and Janet has added herself to my friends list on Facebook.
Update - Thursday Morning
Just had a long conversation with cousin David Turner. As usual with family information, what I had been given was muddled - in this case the wrong university which was why I turned up nothing on the staff list. Google 'David Turner Flinders' and you are swamped with information!
Bushka
Pro

Great! Wonderful News!