Hi,
I just noticed something. There are a couple of trees on A,,y that deal with your Hargreaves family. have you seen them? According to them, Walter married Elsie Paterson and died in Havelock Ont in 1987. He is buried in the Little Lake Cemetery, Peterborough Ontario. Perhaps your other relatives are also buried here. It would be worth checking.
http://www.highlandpark-vrc.com/There is no mention of his parents' death dates on these trees. However, I see the 5 kids you mentioned. One sibling, Douglas, died in Toronto in 1994. I will see if I can find an obituary for him. According to the most extensive tree, there is at least one sibling who is still living. You might want to contact the owner of this tree...
RK
ADDED - just checked for Douglas's obit in the 2 main Toronto papers and didn't find it. Perhaps it was written up in the Peterborough papers. Something to check. The death date is supposed to be July 1 1994.