DesertGold/Moorcroft: https://www.desertgold.us/moorcroft/Moorcroft.html
Moorcroft Pottery CLEMATIS Designed by Walter Moorcroft Cobalt Blue Square Ashtray Approximate Dimensions: 4.625 " (11.748 cm) length 0.75" (1.91 cm) high Circa: 1946-1975 Stoke-On-Trent, England
Marked "Moorcroft Made in England"