When Did Ordnance Maps First Appear?

The first maps that were drawn up by the government's Board of Ordnance were established to help the army over fears of an invasion by Napoleon.  In June 1791, the Board purchased a huge new Ramsden theodolite and surveyors began mapping southern Britain. The first ever published map was a one inch scale of Kent in 1801 and then eventually the whole country was mapped.

After around twenty years still only a third of the country had been mapped to this scale so it was taking a long period.  In 1824 the government decided they needed a detailed six inch to the mile survey of Ireland and the Director General of the Board of Ordnance Major Thomas Colby and most of his staff were sent on this mission.

By 1840 the mapping of England and Scotland was still not completed and the decision was made that all the remaining areas should be completed at the six inch to the mile scale.