Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 160. Statutes of Limitation
The UK Military Manual (1958) states that it is “open to two or more belligerents to agree in a peace treaty, or even in a general armistice, that no further war crimes trials will be instituted by them after a certain agreed date or as from the date of the treaty of the armistice”. 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 641, footnote 1.
In 1967, during a debate in the Third Committee of the UN General Assembly on the question of the punishment of war criminals and of persons who have committed crimes against humanity, the representative of the United Kingdom stated:
As her Government had explained in its reply to the [UN] Secretary-General’s questionnaire, there was no prescription or statute of limitation under the criminal law of the United Kingdom which would preclude persons from being tried for war crimes or crimes against humanity because of the date on which the crime was committed. 
United Kingdom, Statement before the Third Committee of the UN General Assembly, UN Doc. A/C.3/SR.1518, 17 November 1967, § 14.
In a later meeting on the same issue, the representative of the United Kingdom stated:
30. … Her Government was in favour of a convention to the effect that no statutory limitation should apply to war crimes and crimes against humanity irrespective of the date of their commission …
34. Her delegation was … in favour of a general definition [of war crimes and crimes against humanity] and suggested that article I [of the draft convention on the non-applicability of statutory limitations to war crimes and crimes against humanity] should be replaced by the following text:
“No statutory limitation shall apply to war crimes of a grave nature and to crimes against humanity as defined in international law, irrespective of the date of their commission”. 
United Kingdom, Statement before the Third Committee of the UN General Assembly, UN Doc. A/C.3/SR.1547, 12 December 1967, §§ 30 and 34.