Well, I’ve run out of ideas.
I can see no Philip/Phoebe, Joseph/Mary marriages. Nor, censuses for Philip/Phoebe, young Joseph.
I wonder if he left a family behind, running off with Mary, while changing his name. It has happened before.
Say he married, in 1908, doesn’t mean that he did.
Do the certificates actually give the name PARKES as his folk’s surname?
Jamjar