The Papers of William Clarke , who worked in Room 40, are held at Churchill Archives Centre in Cambridge and are accessible to the public. The Papers of Alexander Denniston , second in command of Room 40, are also held at Churchill Archives Centre. The Papers of William Reginald Hall , joint founder of Room 40, are also held at Churchill Archives Centre. Original Documents from Room 40: LUSITANIA case; Naval Battle of Jutland/Skagerrak; The Zimmermann/Mexico Telegram; German Submarine Warfare and Room 40 Intelligence in general; PhotoCopies from The National Archives, Kew, Richmond, UK.