> The UK granted those liberties and some measure of self governance only in the last years of its rule

Hong Kong was nearly[1] granted effectively autonomous status by Britain in the 1960s. China threatened a military intervention should that happen.

1. https://qz.com/279013/the-secret-history-of-hong-kongs-still...

There is a mention in Paddy Ashdown's autobiography describing when he was in the SBS in the 1960s and they were sent undercover posing as tourists to beaches in Hong Kong to evaluate their suitability as evacuation points should China invade.

Britain proposed to turn HK into a self-governing dominion like (non-democratic) Singapore - aka grant HK dejure independence from China - which obviously China would reject since it would circumvent handover. Hence ZhouEnlai labeling it as a plot / conspiracy. Most of the Thatcher memo was about trying to maintain British "control"/administration post handover to help with investor confidence (and British influence).

This QZ article is repeating a fairly disingenuous interpretation of the documents to suggest some missed opportunity for democratic reforms. The original narrative was put forth by VJMedia which bias towards HK local-ism (pro-independence). There was never any effort in the 60s up until years before handover to grant subjects of HK liberties or self-governance within the context of Extension of Hong Kong Territory lease.

Self-rule is sometimes, as would appear in the case of Hong Kong, orthogonal to wildly successful.

I thing there were large scale protests in the 60s, may be 1962 against British rule in HK.

Also did Britain do enough to protect and to take back HK during WW2.

If I remember correctly, HK was only given back to Britain after the final surrender of Japan in WW2. Japan had taken HK following the attack on the same day as Pearl Harbour attack.