This is a good Ironstone pottery mug made by the English factory of Mason's Ironstone, fully marked and dating to the early 19th century, circa 1820.
 
Early Mason's mugs tend to be fairly rare and hard to find.
 
The mug is cylindrical with nominally parallel sides and has the dolphin loop handle. It is nicely decorated in a free flowing style in the highly collected "Japan Basket" Chinoiserie Pattern with hand-painted enamelling in different shades of light and dark cobalt blue, burnt orange and green to the handle.
 
The base of the mug has a blue printed wide spaced M A S O N 'S mark with the large crown and banner, which dates this piece to circa 1820.
 
Dimensions: 3 inches high
Condition: NO Damage, NO Restoration