World War One practice trenches discovered in Derbyshire James Eddy, an aerial photographer with the survey company Bluesky, was asked to take pictures of the area in order to discover if any old mine entrances had been buried, potentially putting the public at risk. He said: "The system we use is often used for archaeological purposes and allows us to see through trees and canopies. We've found World War Two camps down in Surrey before as well. The aerial images were captured using lasers, which were mounted on an aircraft and fired at the ground. Experts then recorded how long it took for the light to bounce back.