Beaumanor Hall were used as a training centre for the Civilian Staff of the Post Office, Civil Service and Merchant Navy. The Royal Corps of Signals, Royal Navy and Royal Air Force were also having military staff trained inside the hall. The huge cellars stretching underneath the whole of the building were used as electricians' workshops. The outbuildings and stables at the side and rear of the hall were used as workshops. These housed aerial riggers, a barracks store, M T Office, transport garage workshop and the instrument mechanics' laboratory. By late 1941, most of the Royal Navy and Royal Air Force military personnel had left for duties at other Y-stations, and the main part of the site became the home of the Royal Signals. Military personnel were still being trained inside the hall for various tasks until the end of the war. In February 1942 the first of the newly trained ladies of the Auxiliary Territorial Service arrived at Beaumanor and were billeted in outlying villages and Garats Hay hall. Beaumanor became one of the most important of the small number of strategic intercept stations, or "Y stations", intercepting enemy radio transmissions and relaying the information to "Station X", at Bletchley Park, for decryption and analysis. It is known that one of the first confirmations of the successful Operation Chastise mission was received here. It is also widely rumoured that this listening post knew details of the Katyn massacre as early as 1941; however, the British government files were not released to the public, as it would implicate surviving perpetrators. By 1943, Room 61 on the top floor of the hall was being used for Radio fingerprinting (Ackbar 13). This new technology was employed to uniquely identify the particular wireless set that was being used to send the transmissions. Special receiving sets filmed the signals as they came in, like a cathode ray tube, and then the signals were captured on film and developed. Light tables were then used to compare the signals in order to verify who was sending them. A civilian from military intelligence at Bletchley Park was in charge of this room. The Radio Direction Finding records room was next door and kept records of the signals' exact locations of origin. In 1940 the use of the hall for all of these different functions allowed for the required specially designed wireless set rooms to be constructed