Hi Sue.
A preliminary result which doesn't add much.
There was a death notice in the Sydney Morning Herald 22/4/1940 MASKELL, Elizabeth Ruth. No detail available, but the index entry says she died 20/4/1940 aged 74. That sounds like your Elizabeth Ruth.
The NSW government site
www.bdm.nsw.gov.au /familyHistory has a death and a marriage in the relevant index.
The death is MASKELL Elizabeth Ruth, ref 12881/1940, Father William, Mother Mary [no surnames given], district Marrickville. Certificates can be bought at that website, and the cost is $AUD27.00 (somewhere around $US19, no idea where we stand with Euros at the moment).
The marriage looks like the one you mention: reference 15953/1928 MASKELL Charles E to SAUNDERSON Vera A, Auburn NSW. Certificates available in the same way and at the same savage cost.
Shipping looks harder at this stage. We will need some timings I think. I guess the earliest Benjamin would have migrated would be the early 1880s, and theoretically the latest is 1928. Did Benjamin and Elizabeth marry in England, or did he meet her here...and if the former, do we know if Charles was born there or here. The site above allows the birth index to be checked up to 1908, and there is no birth for Charles 1880-1908, at least in NSW.
I realise the questions implied above are probably the very ones that you hope to answer of course. I'll keep chipping away quietly.
Alan