Detective-Supt. Petty stated that on the night of April 22 a farmer on a farm adjoining the quarry, hearing a noise of hammering at the office, went there and found the three prisoners in the act of breaking open a substantial safe, in the top of which big holes had been knocked. He called to them to come out, but the only reply he got was from voice which said: "Shoot the —; if you don't I will." Deeming it advisable to withdraw the farmer watched the prisoners leave the building and escape, but they were traced by the police, and when charged said: "None of us got anything."
On the morning after the farmer's discovery, heavy hammers and a crowbar were found in the office, and these had apparently been used to do extensive damage.
Source: findmypast - Bradford Daily Argus, May 5, 1921, Page 1