Surveys being undertaken for a house sale in Cornwall have revealed a previously unmapped collapsed mine shaft under the patio.
The 100m-deep shaft in Scorrier is believed to date from 18th century tin mining activity and is one of a number that have recently opened up in the region.
Environmental reporting specialist Groundsure has said that the shaft is not shown on the earliest OS maps of the area from 1879 but it does show the site to be covered by spoil at that time.
Groundsure research manager Drew Hardy said: “The BGS’ non-coal mining hazard database does highlight the property as being ‘highly likely’ to be affected by mining.”
Work to cap the shaft with concrete is expected to start soon.