Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 120. Accommodation for Children Deprived of Their Liberty
The UK Military Manual (1958) states: “The general provisions of [the 1949 Geneva Convention IV] lay down, inter alia, … that as far as possible families must not be separated but must be given separate accommodation as family units.” 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 56.
The UK LOAC Manual (2004) states: “If arrested, detained or interned for reasons connected with the armed conflict, children must be kept in separate quarters from adults unless they belong to an interned family unit.” 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 9.9.2.
In presenting his government’s report to the Human Rights Committee in 1985, the UK representative explained that while a derogation from the provision on housing detained minors separately from adults had been necessitated by the large numbers of juveniles convicted of terrorist offences, the situation had been remedied by the construction of two new juvenile detention centres. 
United Kingdom, Statement before the Human Rights Committee, UN Doc. CCPR/C/SR.594, 9 April 1985, § 23.
Upon ratification of the 1989 Convention on the Rights of the Child, the United Kingdom reserved the right not to apply Article 37(c) “where at any time there is a lack of suitable accommodation or adequate facilities for a particular individual in any institution in which young offenders are detained, or where the mixing of adults and children is deemed to be mutually beneficial”. 
United Kingdom, Reservations and declarations made upon ratification of the Convention on the Rights of the Child, 16 December 1991, reprinted in UN Doc. CRC/C/2/Rev.4, 28 July 1995, p. 31.
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;
i. Juveniles (under 15) are to be segregated from other apprehended individuals unless to do so would impose solitary confinement on the individual; and
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.
In 2004, in a written answer to a question concerning prison facilities for children in Iraq, the UK Parliamentary Under-Secretary of State, Foreign and Commonwealth Office, stated:
There are no facilities in Iraq under the control of Coalition forces that are solely for prisoners under the age of 18. However, prisoners under the age of 18 are separated from adult prisoners, unless they are housed with family members. 
United Kingdom, House of Commons, Written answer by the Parliamentary Under-Secretary of State for Foreign and Commonwealth Affairs, Foreign and Commonwealth Office, Hansard, 16 July 2004, Vol. 423, Written Answers, col. 1378W.