Slipware Lidded Jar impressed castle mark - Barbican Pottery, Plymouth

Slipware jar with red clay body, impressed mark that looks like a castle by water. Any ideas please?

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Good spot Naomi, the castle symbol sounds right. I'll have to research slipware by a potter with RD initials.

I have got a feeling that Tony Evans'-or whoever Barbican pottery is- might well have worked with John Pollex in at the Barbican Craft workshops, White Lane, Plympooth in the 70's. Lived in Plymouth back then for a long time. John Pollex ran a pottery on the first floor of what was then a back lane. Bought a few pieces as family presents from there. There were always several people working at the pottery. This is exactly the type of slip earthenware they made at the time.