North, which you can see in Sylloge 39. Elmore-Jones, Doubleday, Sazama (a dozen or so sales through DNW), Stewartby, Delme-Radcliffe, Lockett. It depends how far back you want to go. Many named collections had a Plantagenet section, but only a few were devoted mainly to the period. There are plenty of more recent ones such as Robin Eaglen's, so it's more a case of when you want to stop. Most specialised collections will automatically include a number of obscure varieties - that's why they specialised.