Gainsborough Dupont died in 1797.
Gainsborough Dupont was born in 1754.
William Gainsborough died on 1307-09-17.
Thomas Burgh of Gainsborough died on 1496-03-18.
Michael Gainsborough died in June 2004, in Bedford, Bedfordshire, England, UK.
He died of unspecified cancer
Léon Dupont died in 1956.
Émile Dupont died in 1959.
Gabriel Dupont died in 1914.
Clément Dupont died in 1993.
Jaques Dupont died in 2002.
I don't know if this is the artist you are looking for but an artist with the last name Dupont is: Gainsborough Dupont. However, the painting you are describing reminds me of a painting called "Lady with a parasol" by Monet. Hope this helps.
He died at st anne's church