Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 27. Religious Personnel
The UK Military Manual (1958) states: “Chaplains attached to armed forces enjoy all the privileges of the permanent medical personnel.” 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 346, footnote 1.
The UK LOAC Pamphlet (1981) provides: “Chaplains attached to the armed forces have protected status and may not be attacked … They may not be armed.” 
United Kingdom, The Law of Armed Conflict, D/DAT/13/35/66, Army Code 71130 (Revised 1981), Ministry of Defence, prepared under the Direction of The Chief of the General Staff, 1981, Section 6, p. 24, § 13.
The UK LOAC Manual (2004) states that “chaplains … may in no circumstances renounce in whole or in part, the rights secured to them by the [1949 Geneva] Convention[s] or by Additional Protocol I”. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 7.9.
The manual further states:
Chaplains are entitled to similar respect, protection and identification to that afforded to medical personnel. The rules on armlets and identity cards [concerning identification of service medical personnel] apply equally to chaplains. The [1949 Geneva] Conventions are silent on whether chaplains may be armed. United Kingdom policy is that chaplains should be unarmed. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 7.30.
Furthermore, the manual prohibits attacks on medical and religious personnel in non-international armed conflict. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 15.29.