When did the British hand-over sovereignty of Hong Kong back to China?

The story behind the answer

1997 is correct because Britain formally transferred sovereignty of Hong Kong to China at midnight on July 1, 1997, under the 1984 Sino-British Joint Declaration. The handover established the “one country, two systems” framework, promising Hong Kong a high degree of autonomy for 50 years.

Why 1997? The New Territories—most of Hong Kong’s land—had been leased to Britain for 99 years in 1898, setting the expiry in 1997. Although Hong Kong Island (ceded in 1842) and Kowloon (1860) were not leased, governing them separately from the New Territories wasn’t practical, so the entire