I did a bit more searching today, and turned up a couple of tentative candidates...
https://search.ancestry.com/cgi-bin/sse.dll?indiv=1&dbid=8767&h=15844927&tid=&pid=&usePUB=true&_phsrc=bLh3372&_phstart=successSourceGeorge Peagam b. 1839
Pros: right age to be Emily's father, clearly a mariner
Cons: wrong name according to marriage record (should be John), born in Devon (no evidence suggesting *he* wasn't, although we have records suggesting Emily was born in Limerick, Ireland)
This may be clutching at straws, but Emily also had a son named George. And her grandfather and an uncle were both named William, so perhaps a connection to Emily's daughter's name 'Wilhelmina'. William is a common name, George slightly less (as far as I know), and Wilhelmina much less so. I'm also wondering if Emily could have named George as her father but the scribe misheard? I mean, they at least have the same initial sound... yep, I'm trying hard to make excuses here.
Then a few records from
https://www.myheritage.com/names/john_pegum. Sadly I can't view the full information, as I don't have a membership. If anyone could help me out here, I would be much obliged.
John Thomas Pegum, 1867 - 1934
John Thomas Pegum was born on month day 1867, at birth place, to George Pegum and Bridget Pegum (born O'Sullivan).
George was born on October 1 1839, in Limerick.
Bridget was born on ABT1851 1833, in Co. Limerick.
John had 3 sisters: Josephine (?) Pegum and 2 other siblings.
^ I am wondering if one of his siblings could be Emily. Also, just perhaps his father George Peagum could be the Devon one mentioned above?
John William Pegum, 1879 - 1960
John William Pegum was born on month day 1879, to Charles Pegum and Elizabeth Pegum (born Grim).
Elizabeth was born on April 6 1856.
John had 4 siblings: Edith Pegum and 3 other siblings.
^ Could Emily be one of his siblings perhaps?
John Jr. Pegum
John Jr. Pegum was born to John William Pegum and Martha Mattie Pegum (born Brinkman).
John was born on January 11 1879.
Martha was born on April 18 1889.
John had 4 siblings: Evangeline Edith Olson (born Pegum) and 3 other siblings.
^ Could Emily be one of his siblings perhaps?
So, if anyone has a MyHeritage membership, and could perhaps investigate these leads, I would be much obliged!