I worked at Smiths for most of my working life and in the early days… the late 60’s; Radium 226 powder was still being used. The powder was mixed with distilled water and adhesive liquid and applied to the engraved, and already white-filled character with a fine camel-haired brush.
No matter how skilled you were, it was virtually impossible to follow the white outline without some minute spreading of the compound. That is why the Radium application is always very slightly uneven; (it also depended on the thickness of the mix.)
That is why the dread horror stories of licking the brush to get a fine point evolved.
Genuine dial characters are always uneven and the Radium has usually turned a biscuit colour due to ageing and reaction with the adhesive bonding agent.
So; If the calibrations on the dial look too good to be true; they are!… and the instrument in question is probably a screen-printed knock-off, or has been doctored with Letraset rub-down transfers stained to resemble the real thing.
Incidentally as of yet, I haven’t grown a third one and do not glow in the dark!