John Vaughan was an American wine merchant. This is "one of six [portraits] painted by Sully between 1815 and 1823 of John Vaughan (1765-1841)".
<bdi><a href="https://en.wikipedia.org/wiki/en:Thomas_Sully" class="extiw" title="w:en:Thomas Sully"><span title="American painter (1783-1872)">Thomas Sully</span></a>
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between 1815 and 1823 <div style="display: none;">date QS:P571,+1850-00-00T00:00:00Z/7,P1319,+1815-00-00T00:00:00Z/9,P1326,+1823-00-00T00:00:00Z/9</div>
<a rel="nofollow" class="external text" href="http://www.christies.com/lotfinder/lot/thomas-sully-portrait-of-john-vaughan-2067534-details.aspx?intObjectID=2067534">Christie's: SALE 8537 LOT 8</a>