Hi, if you Google Peters Cornish Family you can go straight to his website. It is quite detailed. All the info that I have spells Pierre's surname as de Hamel. Our family is descended from Pierre's son Peter Hammell, later changed to Hammill, which is the way we spell it now. My husband's great grandfather James came out to Australia in 1860 or thereabouts.
Would love to know more about the French ancestry, but I have found it to be complicated. I have searched the family de Hamel/de Bellenglise. They go way back to the Vikings who settled at the village of Hamel on the Somme. I can't make the connection between Pierre and that family but there must be; he had the honorific de or du. I think Pierre's naturalization records show that he came from Peronne which is the right area for him.
Regards and good luck. Keep in touch.