Hong Kong–United Kingdom relations a deeply important role in the formation of the modern Hong Kong. Sovereignty of Hong Kong was ceded to the UK "in perpetuity" on 29 August 1842 through the Treaty of Nanking. The UK further expanded the territory of Hong Kong in 1860 by another cessation, plus a 99-year lease of the New Territories in 1898. The stability, security, and predictability of British law and government enabled Hong Kong to flourish as a centre for international trade. Localisation of teritary institutions, the Hong Kong government and the independent Judiciary in the run-up to the 1997 Handover of sovereignty, caused a
British Forces Overseas Hong Kong internal threats. The greatest test was in 1941, when Japanese forces invaded Hong Kong, leading to the 44-month-long Japanese occupation of Hong Kong. Internal Security was the responsibility of the Hong Kong Government, in particular the Royal Hong Kong Police. It was supported by British Forces in Hong Kong should it be called upon to do so. During the Hong Kong 1967 riots, in which 51 people were killed, the British garrison supported the Royal Hong Kong Police in quelling the disturbance. Until 1995, the safety of much of the Sino-Hong Kong border was the responsibility of the British forces