Colonel Fitzwilliam is sporting a style very similar to the above, particularly in the cut of the jacket. The contrasting velvet trim is something that became more and more popular into the late Regency. The only thing that seems a little odd to me is the pointed detail of his waistcoat. Generally the cut of the waistcoat was straight across, and only about two inches showed, not four as here. Still, the feel is captured, down to the hairstyle and the gloves, hat, and cane.
Portrait of James Belcher, Bare Knuckle Champion of England, c.1803, by Benjamin Marshal (1768-1835). Must have been a very hard man, but looks very elegant, despite his profession - good example of early 19th century dress for english men.