Dear Anne, congrats on your find, which obviously is gusted also as Jakobean by all others here - GREAT!
I have given up regarding this pattern long ago - Walther, Brockwitz, Radeberg, Plötz, Schwepnitz, Jobling, Sowerby, since lately we know Poland, Streit, Stölzle, Schreiber - who else? Today I would say: they ALL produced it in any shape - right?