William and Mary Jane were both born around 1831.
There is record of marriage in Cornwall (1854), but it is not conclusive that it was this couple.
They emigrated to Canada sometime before 1860, because their firstborn (certainly first surviving) was born in 1860 (William) and their secondborn in 1862 (Francis) - both in Bruce Mines.
In order to identify a link to UK (Cornwall or even Devon), I am searching for further info from a marriage record (they may even have been married in Canada!); an 1861 Canadian census; or emigration records from UK (1854-1860)
Thanks for your interest.