Cockroach: Ai Weiwei's new documentary on last year's Hong Kong protests

23 years ago, Chris Patten, the outgoing Governor of Hong Kong, made an emotional farewell speech as Britain handed over its prized colony to China. With the Royal Yacht Britannia purring away in the harbour as the ultimate imperial getaway vehicle, he said, "Now Hong Kong people are going to run Hong Kong. That is the promise and that is the unshakable destiny."

"The promise" he was referring to was the one made in the 1984 Sino-British Joint Declaration, in which China agreed that it would run, in effect, a "one country, two systems" policy when it regained sovereignty of Hong Kong in 1997. It would allow the region to "enjoy a high degree of autonomy" for the next 50 years with its current social and economic systems, free press and lifestyle.

Now, Lord Patten is an intelligent man well versed in politics and would have expected some level of state intervention that blurred the lines of that promise. His democratic developments, for instance, were quickly reversed by Beijing.

But he was sincere and confident when he spoke of an "unshakable destiny".

Five years of living in Hong Kong, a place he grew to love deeply, had taught him, he said, that its people's commitment to an open society was in their "DNA".

He was right.