The debate was obtained by David Davis, a Conservative MP and former shadow home secretary. It's mainly a retelling of the story of Operation Foxden, the FBI plan to tap the new Afghan phone network that was previously covered in this Vanity Fair piece in September 2011:
'9/11: The Tapping Point' (Vanity Fair, September 2011)
The topline of that story is speculation that, were it not for rivalry between the FBI and CIA, the US might have been able to gather sufficient intelligence to prevent the 9/11 attacks.
Davis's focus is the 'state secrets privilege' that initially prevented discussion of Foxden in open court and led to the collapse of a civil case in 2003.
The context of the MPs' debate is a proposal by the UK's Ministry of Justice to substantially expand the scope of "sensitive" material that the Government can protect from disclosure in British courts, as set out in this Green Paper:
Justice and Security Green Paper (Ministry of Justice, October 2011)