“B” is for “BROWN BETTY”…
Ordinary teapot made of red clay native to England, which dates back to the end of the 18th century. The original unglazed teapot was made out of red clay from the Bradell Woods area in Stoke-on-Trent, Staffordshire and is still made in Stoke-on-Trent with the same clay, but is glazed. British believe that Brown Betty makes the best tea because of the type of clay that is used and the shape of the pot.
Source – Tea Dictionary by James Norwood Pratt