This globe mark was used by Minton from 1863-1872. In 1870 Minton opened an art studio pottery which welcomed both new and established artists to design wares. Many signed their work. It's possible that William Leigh or his son, Edmund, produced some pieces. They all worked in the Stoke on Trent potteries, and Leigh took over Burleigh Pottery in 1862 with a partner to form Burgess & Leigh. You could inquire with the pottery archives there today.