Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 100. Fair Trial Guarantees
Section K. Public proceedings
The UK Military Manual (1958) provides that if the trial of a prisoner of war is held in camera, “the Detaining Power shall notify the Protecting Power” of the reasons why. 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 229.
The UK LOAC Manual (2004) states in its chapter on the protection of civilians in the hands of a party to the conflict:
In the case of penal offences relating to the armed conflict, the basic principles of natural justice must be observed … These principles include the following: … anyone prosecuted for an offence shall have the right to have the judgement pronounced publicly. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 9.6.
In its chapter on internal armed conflict, the manual states: “Indispensable judicial guarantees include as a minimum … public judgment.” 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 15.30.5.
In 2004, during a debate in the House of Commons, the UK Parliamentary Under-Secretary of State for Foreign and Commonwealth Affairs stated regarding the trial of UK citizens before a US military commission:
[T]he view of the Attorney-General was that the military commission, as constituted, would not provide the type of process that we would afford to British nationals. We have been attempting to ensure that the legal process will respect the human rights of the detainees, including the right to a fair and public hearing by a competent, independent and impartial tribunal, established by law. 
United Kingdom, House of Commons, Statement by the Parliamentary Under-Secretary of State for Foreign and Commonwealth Affairs, Hansard, 24 March 2004, Vol. 419, Debates, col. 307WH.