Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 49. War Booty
The UK Military Manual (1958) states:
All articles captured with prisoners of war and not included under the term “personal effects” are known as “booty” and become the property of the enemy government and not of the individuals or unit capturing them. 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 142.
The manual also provides:
Public enemy property found or captured on a battlefield becomes, as a general rule, the property of the opposing belligerent. Private enemy property on the battlefield is not (as it was in former times) in every case booty. Arms and ammunition and military equipment and papers are booty, even if they are the property of individuals, but cash, jewellery, and other private articles of value are not. 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 615.
The UK LOAC Pamphlet (1981) states:
PWs [prisoners of war] should be searched and disarmed and their military papers and equipment removed.
… A PW is entitled to keep his identity card, his personal property, decorations, badges of rank, articles of sentimental value and military clothing and protective equipment such as steel helmets, gas masks and NBC clothing. 
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 8, p. 29, §§ 10 and 11.
The UK LOAC Manual (2004) 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, and, where not in their possession, cards must be issued by the captor (see further, sub-paragraph i);
(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.
e. All other items of military equipment may be confiscated. That includes arms and ammunition, non-protective military equipment, military documents such as orders, maps, and diaries containing military information. They become the property of the capturing government, not the individuals or units capturing them. Items taken should be tagged. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 8.25.
The Report on UK Practice refers to a letter from a UK army lawyer which noted that UK courts-martial were held following the Gulf War for the smuggling of AK-47s. 
Report on UK Practice, 1997, Letter from an army lawyer, 24 February 1998, Answers to additional questions on Chapter 2.3.
The Report on UK Practice refers to a letter from a UK army lawyer which noted:
The current view seems to be that units may lawfully seize enemy property on the battlefield and retain it as booty, but individuals doing the same run the risk of being charged with looting. Retention by units and formations of booty is subject to approval by Government whereas appropriation of property by individuals on the battlefield is strictly illegal. 
Report on UK Practice, 1997, Letter from an army lawyer, 24 February 1998, Answers to additional questions on Chapter 2.3.
[emphasis in original]