Sir Thomas Lawrence (1769-1830) was one of those painters fated to be honored in his own time and rapidly neglected following his death. I originally titled this post "Lawrence, the Forgotten" but decided that was too extreme because he never became utterly unknown. Indeed, his some paintings have resided in important collections since the day they left his studio.
Somewhere I read that Lawrence's reputation fell because he specialized in painting portraits of the famous and wealthy. And maybe because of his ties to George IV as regent and king. Could be, though not many artists of his time devoted careers to depicting peasants and shopkeepers. That subject matter started coming into vogue around the time he died, so it's not really fair to fault him on that score.
Perhaps a more realistic possibility is that he wasn't Sir Joshua Reynolds who, along with Sir Thomas Gainsborough, dominated English portraiture for a good part of the 18th century: call it Reynolds-or-nothing for many critics. Then too, he had strong rivals such as Sir Henry Raeburn during his career, and these might have diminished his later stature.
For what it's worth, the Lawrence portraits I come across in major museums strike me as quite good (though they probably represent some of the cream of his crop). Like most artists, quality of his work varies; to see a cross-section (along with those ringers that creep into a search) Google on his name and then select Images.
The Wikipedia entry for Lawrence is here, and an item from the Telegraph about his swingin' bachelorhood is here
Below are examples of his work.
This was painted the year of Waterloo and probably is the definitive portrait of the Duke.
This is almost surely unfinished, so it offers a window into Lawrence's technique; try clicking to enlarge.
Another unfinished work. Nowadays painters are urged to "work the whole canvas" while developing a painting. Portrait artists, given the problem of getting enough sitter-time, often have little choice but to get the face done first and then complete the work as best they can if the sitter can no longer sit.