If I remember correctly, the Royal Flight used to polish the Andover lower fuselages to a mirror finish, it was found during some NDT inspection that a fair amount of the metal had been polished away resulting in the need for extensive reskinning, they than painted the lower half grey.
Little tip when polishing and you remove all the black residue you get, instead of going through a million cloths, use one and put flour, yup that's right, household flour, plain or self rising
in the cloth, that will take off and absorb the black residue and speed up the process.