Hi Stuart. Interesting plate. We have three versions of this pattern in our database, known as Zeus in his Chariot. One is by Spode, probably the best known maker of this series of Greek patterns. The others are maker unknown - one does have the impressed H as your plate does, the other unmarked but with the three stars surrounding Zeus, which the other versions don't have. None of these have the vermicular surround your example does, but printed flowers as in the Spode version. There is a plate like yours (except for the vermicelli) illustrated in Friends of Blue Bulletin #135 from April 2007 - same stars, same impressed H - and it is tentatively attributed to the Glamorgan Pottery in Swansea. Morton Nance in his book on Swansea said the impressed H is a mark from that pottery, and Helen Hallesey shows two plates in her book on the Glamorgan Pottery that have an impressed H mark in addition to the Baker, Bevans & Irwin maker's mark. So at the very least Swansea is a possibility though I'm not sure that's a firm attribution.