Secret committee
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
A secret committee of the house of commons is a committee specially appointed to investigate a certain matter, and to which secrecy being deemed necessary in furtherance of its objects, its proceedings are conducted with closed doors, to the exclusion of all persons not members of the committee. All other committees are open to members of the house, although they may not be serving upon them.
Brown.