The flag is dated 1835, 1839 and 1844, but may have been reversed, perhaps only in 1839. Reversal would make it the house flag of John H. Shaw and J.H. Shaw & W. Folger. M637 comes from the 1840–1850 painting.
Mount Vernon is described as operating from Nantucket from 1837, although the same account includes a 1835 owner and agency entry. Owners included William Folger, ? Folger and ElishaSwain. William Folger and then John H. Shaw acted as agents; she was sold to Mattapoisett in 1848.
Keep the explicit scope label independent; no alias or company identity is inferred.