I think the lesson is these kind of big time diplomatic discussion over territory changing hands MUST be backed with credible threat of violence, else no one is going to give up anything no matter how much of a smooth talker your negotiator is.
According to Shilao, during the 1997 Hong Kong handover the Hong Kong Garrison was subject to intense EW from . Even though this was all agreed upon many years before and everything went according to the agreed protocol the Brits are still going to be an asshole about it. So you can imagine if you don't have credible threat of violence and think you can just nicely talk them into giving up Falkland Island you have another thing coming.
The exact quote:
in no more than one or two years time the Chinese government would formally announce their decision to recover Hong Kong.
Not necessarily violence. I think the bigger implication was whether the British were willing to risk losing everything (businesses, etc.) by maintaining a sovereignty claim.
TBH, China didn't had Thatcher at gunpoint.
If the UK refuses to return Hong Kong back to China, then the PLA will just march their troops and tanks across the Shenzhen River and right onto the streets of Kowloon. And what can the UK even do about it?
Sure, the UK did drew up plans to nuke China in case Beijing orders the PLA to crash into Hong Kong in the 1950s and the early-1960s.
But when Thatcher visited Beijing in September 1982 - China was estimated to have 200+ nuclear warheads, and had just introduced the DF-5 ICBM, which puts all of the British Isles within range of a Chinese nuclear attack. Besides, Hong Kong is much, much farther away from the UK than the Falklands/Malvinas are - There is zero hope for the UK to relieve their garrisons in Hong Kong if Beijing decides to reunite Hong Kong forcefully, then and there.
Plus, the early-1980s was the honeymoon period between China and the US-led West, and the US-led West needs China's support to stand against the USSR. It was definitely not in London's interests to force China back into the WTO camp.
To sum it up - It was Thatcher (and the UK in general) that didn't have a choice in the first place.
As you can see in the link above (and there are others like it for those that have a distaste for CNN), UK never had any illusions about keeping HK and actually the Falklands war did have an indirect impact on he negotiations.
What's more interesting is that Zhou Enlai always had a lot of foresight into how he could use HK to the PRC's advantage. First, they never invaded HK in the immediate aftermath of the war. Then when the British had considered giving HK more political freedom in the 50's, Premier Zhou could foresee how this could be used as a lever to be used against the PRC and strongly advised against it. When the leftist riots gripped the city in the 60's, he actually moved against them. He also guaranteed water and food delivery to HK even when PRC was poor. This guy had a 50 year plan, amazing...
CNN said this on the point of democracy:
“very unfriendly act,” premier Zhou Enlai reportedly told British officials in 1958. Another Chinese official in 1960 threatened potential invasion if the UK attempted to introduce greater democracy to the colony.
The full background is actually this ():
A self-governing Hong Kong would, in their opinion, open its doors to Chiang Kai-shek and the Americans,' according to British Embassy documents concerning the meeting.
'China wished the present colonial status of Hong Kong to continue with no change whatsoever . . . the enormous American Consulate-General in Hong Kong was merely a base for subversive activities in China and this would become worse if Hong Kong was self-governing.