Qing/Manchu-China's status.

Post-Opium Wars Qing Dynasty China remained an empire, albeit a weak empire.  Internal corruption, opium addiction, and economic destruction contributed to the losses of this war.  Despite claiming victory over Qing/Manchu Dynasty-China, the only thing the British Empire controlled was trade.  Central to Qing-China's economy is trade, yet the control wasn't as tight as the British Empire thought it was.

Burbank and Cooper never stated outright nor made implications about Qing-Dynasty China's status as a colony of the British Empire.  Trade fell to the British, but only part of it went to them.  After the First Opium War (c. 1839) and perhaps before that, Chinese merchants fled to Hong Kong as a safe haven against complete domination of British Imperial policy.

Between the aftermath of the First and Second Opium Wars, British "colonizers" settled in Hong Kong as well.  They allowed residence to the Chinese merchants under the pretenses of segregated living areas.  This allowed the merchants to conduct business and accumulate wealth.

Now, if the British denied any right for Chinese merchants to reside in Hong Kong, the economy might still as well fall to British control.  However, because the British couldn't possibly gain foothold of every part of Qing-China, trade posts undetected by British patrols go unnoticed because of central fixation on harbor ports.

Chinese merchants gained the advantage of continuing their businesses over in Hong Kong, despite circumstances.  Would it be much safer to deem Qing-China then as an outpost of the British Empire, rather than a colony?  A colony establishes a settlement of the peoples dominant over the opposing country's empire or rule.  This includes complete control over politics, rule, and economy.  Opposition to British rule lasted for a while and resentment against British-rule almost fades away by the Cultural Revolution, in some aspects.

Burbank and Cooper also mentioned that Chinese political activity, with British intervention, went on. Sometimes in the absence of British presence, political activity still fell to the Qing-Chinese, as in the case of the decisions of the Boxer Rebellion.  Upon the crushing defeat of the Boxer Rebellion, Hong Kong-based merchants relied on trade to retain their part in the economy of China.