The White house was referred to as Camelot in the time of JFK. Castle Lock could also be a reference to Chess which Q is fond of.
The Last Castle is a 2001 American action drama film directed by Rod Lurie, starring Robert Redford, James Gandolfini, Mark Ruffalo and Delroy Lindo.
The film portrays a struggle between inmates and the warden of a military prison, based on the United States Disciplinary Barracks at Fort Leavenworth.[2] A highly decorated U.S. Army Lieutenant General, court martialed and sentenced for insubordination, challenges the prison commandant, a colonel, over his treatment of the prisoners. After mobilizing the inmates, the former general leads an uprising aiming to seize control of the prison.
The last idea I have deals with the name Castle, but I cannot go further due to security clearance issues. Just know that Castle Lock may be the name of the operation being run.