Re:lf. The British (and Australian) maps were prepared for military purposes
Not quite. The staff of the OS were originally recruited to make maps for such purposes during WWI. But.
Between the wars, there was a fear that because the government had no legal reason to maintain the OS in peacetime the skill-base would be lost*, so they came up with a spiffing wheeze; a proposal to map the entire British Isles to a scale of one inch to one foot.
In the very late sixties they were nearly done, when the country decided it was going to go metric in a bid to make the French more receptive to EEC membership, and the OS were tasked with doing the job over to 1:50,000 scale.
The original OS 1 inch to one mile scale maps had bright red covers. In order that there should be no confusion (the overall coverage of any given map was slightly different in the newer scale) the newer 1:50,000 ones had bright pink covers.
For a glorious couple of years you could actually get both, though the red ones quickly disappeared once the series was complete. How do I know? Because I was there, and a keen Outward Bounder at the time.
You get a truly gobsmacking amount of information on one of these maps, enough that should one have a selection of landmarks including churches (ruined or otherwise, with a tower or spire or neither), power lines (the national and super grids were distinguishable), a railway line (especially if it ran over an embankment or through a cutting), a windmill (ruined or working) or a road (minor, major, A or B) or a raft of others (rivers, lakes, canals) a compass is actually superfluous. And all before you start examining the contour information to identify hills by their steepness.
I bought one for every single place I worked a contract and the route to it from Coventry. I can show you on the one of Land's End where to stand almost to the yard in order to see <i.why</i> they call it The Lizard. The one I have of Corris is from before the heritage railway was up and running, so the railway isn't shown - but the ancient trackbed is along with the reasons it was built in the first place.
More modern ones even include scenic lookouts for the traveler with a camera.
The American GS maps are nice, but not *as* nice. Different reason for making them, see?
Yes, I miss the OS map rack in W.H.Smiths.
* If anything illustrates a difference in attitude between then and now, this does.