This pair Regency chairs is to a difficult design by Thomas Sheraton (1751-1806) rarely actually produced. This complex C form with inset tablet and reeded splats is an ambitious piece of joinery, and attests to a skilled craftsman. This design was made pre-mortem*, so, before 1806, but not published till 1812, "by J. Taylor at the Architectural Library". I expect our excellent pair of parlour chairs were made not much after the publication of the design in 1812.
*The excellent "Pride and Prejudice and Zombies" nothwithstanding.