I've found a James Davey on the 1851 Census in Jersey, but i am not sure if it is the right family. There's a couple of James Davey's on the 1851 Census but the one that stood out was:
James DAVEY, age 32, born in England, Occupation: Fisherman, Living in the parish of St. Martins.
There is no sign of a Nancy Marguerite Davey but there is a a Marguerite Davey listed as his wife aged 27, place of birth: British SUbject.
His children:
James William Davey, Son, Scholar, aged 6, born in St. Martins
Marguerite Davey, Daughter, aged 4, born in St. Martins
Charles R. Davey, Son, Aged 2, bron in St. Martins
Emily Davey, Daughter, 7 months old, born in St. Martins
There is know sign of them in the 1861 Census.
As i said i am not sure if this is the correct Davey family as there are quite a few.
There is no marriage of a James Davey and a Nancy Marguerite Laine on the OPAC (even the one at the archives which is updated every other month) i cant seem to find a marriage for them either in the Marriage index of St. Martins or St. Helier.