This is the furnace mentioned in Don Davies' audio account. A German aircrew member who had been shot down was being treated as a patient in Morriston Hospital and described how the fire from the furnace guided their bombers to Swansea to the patient next to him. The patient, who was well known to Don and his family, then reported this to the authorities. As a result, the furnace was quickly capped so that its flames were not visible to the Luftwaffe making subsequent raids.