Only other thought would be if Britain has become first resource in EDB list for you. I did have a, to my mind, completely inexplicable problem where adding in EDB
temple_of_horse_shrine requires factions { huns, } or building_present_min_level temple_of_horse temple_of_horse_shrine
(to make other factions able to build over existing shrines etc.) Stopped the game recognising the first resource in the EDB list if it was actually used in DR - putting an un-used resource first in list made it all work fine!
So there might be something to do with the ordering of the list?!