Are there any John Constable paintings from the late 1700s?
Constable was born in 1776, which would have made him only 24 in 1800. He worked as a mapmaker and topographical painter. Chances are his work from his youth is not going to be all that easy to find, if there are any to be found. The paintings and subjects he is most famous for were not done until the 1810’s and 20’s. You may never find anything from the 1700’s. You might try to get some response from the Victoria and Albert Museum in London. They hold most of his works.