Ordnance Survey is 235 years old today, 21 June.
These stamps were produced in 1991 and show snippets of a map of the village of Hamstreet in Kent from 1816, 1906, 1959 and 1991. Chosen because the very first map produced by Ordnance Survey was of the county of Kent. Text and image from https://postalmuseum.org/ @map_enthusiasts #maps #OrdnanceSurvey #Kent #England
I guess the last one switched from “1 inch to 1 mile” to “2cm to 1km”, which is why it is slightly larger scale.