So....
It is entirely possible that Edward Cecil G may NOT have told his family in Tasmania about his second marriage ... and thus they were unaware that he had three English born children... AND he didn't keep in contact with his Tas family either, for THEY thought he had disappeared "beyond the seas"in May or June 1908 ... but in fact he disappeared during WWI ...
So we are looking for ECG perhaps using an alias (umm ... RANSOM was his mum's m.s., but there's always Mrs G # 1's m.s. or Edward Cecil GRANT or ....

) ...
Interesting though that Edith's second marriage says she was a widow ... any possible clues as to when she became one ... any faint writing or obscure marks somewheres. I presume that the Registrar would have asked her about that .... but it was during war time, so it would be easier for him to accept say "he fell at the front" .... BUT he ought to have checked .... Back in pre civil registration days and when the penal colonies were still just that, if either party was NOT either a bachelor or a spinster, then the widowed party needed to sign various legal documents before the licence to marry was approved. This was based on UK instructions issued by WHITEHALL... And the original parish record was meant to include the licence # so that those affidavits etc could be easily found if anyone came forward to make a complaint of bigamy...
WWI UK medal cards (but he would have been quite old, so had to fib on enlistment papers if that was his way to bolt )
OR
in any of the Dominions WWI records
OR
as a merchant navy chap
OR
............................. hypothetically there's always Plan D, E, F or any of the other remaining letters of the alphabet
We can eliminate the one at Five Dock NSW in 1913 ...
BUT we cannot eliminate the one in 1908 on the SS Suffolk...
AND we need to think of where-else to look, or else we have yet another ERNEST on the books ...
Ummm.... Perhaps there's an RChatter with some deep knowledge of those records in the Nova Scotia archives ........ for crew lists etc.
Cheers, JM