Very nice piece of history not only for the pottery but also for the advertising.
William Powell established a pottery shop at Thomas Street around 1816, later moving to Temple Gate in 1829/30. 
William Powell is credited with the development of the "Bristol Glaze" around 1835, which allowed for a more appealing glaze and a unique two-tone effect on stoneware. 
Measuring 26cm high with 17cm diameter