This is a beautiful Royal Crown Derby Imari Porcelain Cup and Saucer. Although, I am not an expert on Royal Crown Derby or Imari through internet and book research I believe this set to be circa 1806 -1888 ( Ref: Godden Book "Encyclopaedia of British Porcelain Marks" p. 201 and internet " Royal Crown Derby Antiques Marks"). The red marks on the bottom of the Cup and Saucer are partially missing, but there is enough to identify the date stated. The crown symbol is there, the red D, and the saucer has the number 56. The cup also has a number, but I can only make out the 2nd number 3.
The Cup measures 2 1/2" tall with a 3 1/2" opening. The Saucer is 5 1/2" diameter. The Cup has a square handle with a curl on the top. The Cup is called "London Style". The hand painted pattern is divided into panels featuring a floral design using iron red, dark and light blue, green, and lots of gilding. I read that Imari decorations were copied from textiles popular in Japan at the time.
The condition is wonderful for its age. There are no chips or cracks. The gold rim of the saucer shows some wear. The outside bottom of the cup is heavily crazed, but does not show on the inside. Collectors, this is really a nice item of Antique Imari.