It was orderly, with stairways, hallways, and elevators going somewhere.
It's logical, really: in a house as orderly as Downton, there would be a hierarchy below the stairs just as there would be above.
A lightning bolt striking his Manhattan apartment ends his tidy, orderly self-centered academic life for good.
"military attendant who carries orders," 1781, short for orderly corporal, etc. Extended 1809 to an attendant at a hospital (originally a military hospital) charged with keeping things in order and clean. See orderly (adj.).
orderly or·der·ly (ôr'dər-lē)
An attendant in a hospital.