A very interesting Derby porcelain cup and saucer.
The pair are decorated in French Sprig pattern, and marked with crown, crossed batons, dots and D in red.  The surprise is that these are Duesbury's best duck egg porcelain, dating to the late 18th Century.
When Robert Bloor took over the Derby factory in 1815 and in order to recover his investment as quickly as possible, set about having the stock piles of porcelain he had inherited of as yet undecorated Derby, painted in simple patterns and sold.  This cup and saucer bears testament to the early time of Bloor's ownership of the factory.  Please see "English Porcelain and Bone China 1743-1850 by Bernard and Therle Hughes.
In excellent condition throughout.