Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 55. Access for Humanitarian Relief to Civilians in Need
Section C. Access for humanitarian relief via third States
The UK Military Manual (1958) states:
If the whole or part of the population of occupied territory suffers from shortage of supplies, the Occupant must agree to relief schemes being instituted on their behalf and must facilitate such schemes by all the means at his disposal. The schemes in question will consist in particular of the provision of the consignments of foodstuffs, medical supplies and clothing … All parties to [the 1949 Geneva Convention IV] must permit the free passage of such consignments and must guarantee their protection. 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 541.
In 2003, in reply to a written question in the House of Commons asking “what plans [were] in place to ensure early access for UN agencies and international aid agencies into Basra”, the UK Secretary of State for International Development wrote:
Most humanitarian agencies require a permissive security environment before they can operate in Iraq. The Office of the UN Security Co-ordinator (UNSECOORD) provides security advice to the UN humanitarian agencies. Security updates are also being provided through the Humanitarian Operations Centre in Kuwait. NGOs are being issued passes to cross the Kuwait/Iraq border by the Humanitarian Operations Centre in Kuwait. Once the situation allows, NGOs will need to undertake their own security assessments before engaging. 
United Kingdom, House of Commons, Written answer by the Secretary of State for International Development, Hansard, 10 April 2003, Vol. 403, Written Answers, col. 389W.