Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 122. Pillage of the Personal Belongings of Persons Deprived of Their Liberty
In its chapter on the protection of civilians in the hands of a party to the conflict, the UK LOAC Manual (2004) states:
Internees must be permitted to keep articles of personal use, especially those of a personal or sentimental value. They may also keep a certain amount of money in the form of cash or coupons to enable them to make purchases. Money, other valuables and identity documents may only be taken away in accordance with established procedures, detailed receipts being given. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 9.43.
On prisoners of war, the manual states:
The following action is to be taken in respect of prisoners of war when first captured:
d. The property listed below must remain in their possession:
(1) clothing, military and civilian including that for their special protection such as NBC suits;
(2) protective military equipment, for example, steel helmets, flak jackets and respirators;
(3) feeding utensils, ration packs and water bottles;
(4) badges of rank and nationality, military insignia;
(5) decorations and medals;
(6) identity cards, and discs …
(7) personal property, which the prisoners of war are able to carry with them, such as spectacles and articles of sentimental value like personal letters and family photographs, but see sub-paragraph f;
f. Personal property may only be removed for security reasons; this would include articles which could be used as weapons, such as razor blades and sharp knives, or which could affect security, such as cameras.
g. Sums of money may only be taken away on the order of an officer. The amount taken must be recorded in a special register and an itemized receipt, showing the name, rank and unit of the person issuing it, given. Money that is the private property of the prisoner of war is either credited to his account or returned to him at the end of captivity …
h. Articles of value may be taken for safe custody only. A record must be made and a receipt given. The articles must be returned intact at the end of captivity. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 8.25.
The UK Army Act (1955), as amended in 1971, provides:
Any person subject to military law who –
(a) steals from, or with intent to steal searches, the person of anyone … captured in the course of warlike operations, or … detained in the course of operations undertaken by Her Majesty’s forces for the preservation of law and order or otherwise in aid of the civil authorities, … shall be guilty of looting and liable, on conviction by court-martial, to imprisonment or any less punishment provided by this Act. 
United Kingdom, Army Act, 1955, as amended in 1971, Section 30(a).
The UK Air Force Act (1955), as amended in 1971, provides:
Any person subject to air-force law who –
(a) steals from, or with intent to steal searches, the person of anyone … captured in the course of warlike operations, or … detained in the course of operations undertaken by Her Majesty’s forces for the preservation of law and order or otherwise in aid of the civil authorities, … shall be guilty of looting and liable, on conviction by court-martial, to imprisonment or any less punishment provided by this Act. 
United Kingdom, Air Force Act, 1955, as amended in 1971, Section 30(a).
The UK Armed Forces Act (2006) states:
4 Looting
(1) A person within subsection (4) commits an offence if, without lawful excuse –
(a) he takes any property from a person who has been killed, injured, captured or detained in the course of an action or operation of any of Her Majesty’s forces or of any force co-operating with them; or
(b) he searches such a person with the intention of taking property from him.
(4) A person is within this subsection if he is –
(a) a person subject to service law; or
(b) a civilian subject to service discipline. 
United Kingdom, Armed Forces Act, 2006, Section 4.
In 2010, in its closing submissions to the public inquiry into the circumstances surrounding the death of Baha Mousa and the treatment of those detained with him by UK armed forces in Iraq in 2003, the UK Ministry of Defence stated:
12. The treaties setting out rules of IHL are supplemented by rules of customary international law (CIL), i.e. rules which are recognized as binding by States, even though they do not appear in treaty texts. … [I]n relation to the rules described below the Government accepts that they reflect CIL. It is suggested that the rules which are of most relevance to this inquiry are:
12.16. … Pillage of the personal belongings of persons deprived of their liberty is prohibited. 
United Kingdom, Ministry of Defence, Closing Submissions to the Baha Mousa Public Inquiry on Modules 1–3, 25 June 2010, §§ 12 and 12.16, pp. 28 and 32.
[emphasis in original]