Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 119. Accommodation for Women Deprived of Their Liberty
The UK Military Manual (1958) provides: “When men and women prisoners of war are accommodated in the same camp, separate sleeping quarters must be provided.” 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 148.
The UK LOAC Manual (2004) states in its chapter on the protection of civilians in the hands of a party to the conflict:
Women arrested, detained or interned for reasons connected with the armed conflict must be kept in separate quarters from men and under the immediate supervision of women. In cases where families are detained or interned, they should, whenever possible, be held in the same place and accommodated “as family units”. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 9.8.1.
On prisoners of war, the manual states: “Accommodation for prisoners of war is required to be at least as good as that for the forces of the detaining power billeted in the same area. Women must have separate sleeping quarters from men.” 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 8.49.
In its discussion on judicial proceedings against prisoners of war, the manual further states: “Women sentenced to confinement are to be confined in separate quarters from men and must be under the supervision of women.” 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 8.144.
In its chapter on occupied territory, the manual states:
Protected persons who are detained either because they are awaiting trial or as a result of a custodial sentence are entitled to have the following treatment:
f. women must be kept in separate quarters from men and under the direct supervision of women. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 11.74 11 .
With regard to internal armed conflicts in which the 1977 Additional Protocol II is applicable, the manual provides:
Those responsible for the internment or detention are also placed under obligation “within the limits of their capabilities” to “respect” some further provisions relating to persons interned or detained for reasons relating to the armed conflict. These are:
a. that except when men and women of a family are accommodated together, women shall be held in quarters separated from those of men and shall be under the immediate supervision of women. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 15.41.
In 2004, in a written answer to a question concerning “the document issued to service personnel announcing the ban on the use of hoods for Iraqi prisoners”, the UK Secretary of State for Defence stated:
An amended Standard Operating Instruction on the Policy for Apprehending, Handling and Processing Detainees and Internees was issued on 30 September 2003. The following section of the document contains the relevant information.
a. Apprehended individuals are to be treated at all times fairly, humanely and with respect for his or her personal dignity;
h. Females are to be segregated from males;
j. It is a command responsibility to ensure that all apprehended individuals are treated in accordance with these principles. 
United Kingdom, House of Commons, Written answer by the Secretary of State for Defence, Hansard, 7 July 2004, Vol. 423, Written Answers, col. 721W.