It appears to be from "The Military Administration of England" with regional headquarters in London, Birmingham, Newcastle, Liverpool, Glasgow and Dublin. Though Dr. Six and his staff would be based in London, Manchester, Birmingham, Bristol, Liverpool and either Edinburgh or Glasgow which suggests different plans.You have a source for this?
There were numerous variations on the occupation plans, unification of Ireland versus retention of NI, autonomous Western England, independent Scotland, partial occupation with an internal border et cetera.