Career
He then established his own business, John Janvrin and Company, in fishing and retail on Cape Breton Island. Janvrin held a number of offices during his time in Cape Breton. Janvrin Island belonged to John Janvrin at one point and is now named after him.
While carrying on his various commercial activities after his 1815 return to Jersey, Janvrin became increasingly interested in banking and brokerage.
As time went on, the Janvrin family began moving out of mercantile trade into banking and brokerage in London and on Jersey. Around the middle of the 19th century it concentrated its energies and capital in that sector of the economy.