How could US (or British for that matter) HUMINT operate in places such as PR-China
By taking advantage of the pervasive corruption in China to bribe Chinese nationals ("agents") who are cross-checked for their ability to provide the U.S. or British citizens ("operatives") with information. That's how the C.I.A. has long gathered a lot of its human intelligence in a lot of countries. It doesn't always work, but neither do any other country's attempts to gather intelligence always work against the United States or Britain.
By taking advantage of the pervasive corruption in China to bribe Chinese nationals ("agents") who are cross-checked for their ability to provide the U.S. or British citizens ("operatives") with information. That's how the C.I.A. has long gathered a lot of its human intelligence in a lot of countries. It doesn't always work, but neither do any other country's attempts to gather intelligence always work against the United States or Britain.