One of the first ports of call for any investigation into the history of a historic house is that wonderful British institution – the Ordnance Survey map. We have the threat of impending invasion from Revolutionary France to thank for this helpful resource. The government of the late eighteenth century recognized the need for accurate maps to aid in the effective defence of the nation and ordered its Board of Ordnance to produce a comprehensive survey of the country. The Ordnance Survey was born.
In the mid-Victorian period, the first edition of the small scale 1:2,500 plans (ten times more detailed than the OS Explorer maps you find in the shops these days) began appearing. The 1:1,250 town plans provide even more detail, but both sets of maps show individual houses. Three more editions of the 1:2,500 scale maps were produced a regular intervals for all counties and can be used to trace changes to properties as extensions were added and old, disused parts of a house were demolished and/or rebuilt. As the gap between editions was sometimes as little as 10-15 years, the survey can help narrow down the time period to be searched for relevant building plans where they’ve survived.
The 1:10,000 scale maps – which were also produced regularly from the late 1800s – show few details of individual properties, but are particularly useful for studying changes to the wider rural landscape and the expansion of communities in the nineteenth and twentieth centuries.
Local archives usually have a good collection, though many are now available digitally.