Le Vesconte was born at Saint Aubin in Jersey in 1822, was educated in St Helier, and went to Arichat on Isle Madame at the age of 12. He worked in his family's company, which sold goods to fishermen and imported and exported goods, including dried fish.
He was put in charge of the operation at Arichat in 1855. He was elected to the Nova Scotia House of Assembly in 1863 for Richmond County and served as financial secretary from 1863 to 1864. He was elected to the House of Commons in an 1869 by-election after the death of William Croke and retired from politics in 1874.
He died in Arichat, in 1879.
His grandson, Isaac Duncan MacDougall, later served in the House of Commons.