A few years ago, George Osborne announced that Britain’s relations with China were entering a “golden era”. On Thursday, his successor as chancellor gave a more measured assessment: they are “complex”, Philip Hammond said, noting that they “had not been made simpler” by the defence secretary Gavin Williamson’s threat to deploy an aircraft carrier in the South China Sea.

Britain, blanching as Brexit approaches, is more anxious than ever to keep Chinese cash flowing. Diplomats from other nations say London is already less willing to criticise Beijing because it knows how much it will need it. Yet some of the lustre is coming off bilateral dealings, as it is from China’s relationships elsewhere. The Trump administration is viscerally hostile, but Beijing’s increasingly repressive turn at home and forcefulness abroad has alarmed many who were more sympathetic to it.

In its own region and in the west especially, there is growing concern about China’s attempts to form the views of the public and politicians. The implications for the UK are laid out in a report from the Royal United Services Institute (Rusi) this week, which considers everything from involvement in critical infrastructure to the funding of academic research to “elite capture”, as former politicians and officials are hired for lucrative jobs. As it notes, some of these activities are legitimate. Some bring benefits. But others constitute unacceptable interference. Drawing the line is not easy, but must be attempted, and sooner rather than later. In Australia, a scandal over political funding from a Chinese businessman has led to the resignation of a senator, new laws on donations, and the barring of the donor. In Sweden, the government is investigating its ambassador to Beijing for arranging “strange” unofficial meetings between the daughter of a detained citizen and Chinese businessmen who claimed they could help to secure his release.

Britain has so far done relatively little to determine how China is seeking to shape views in its own interests, whether we are prepared to accept these means, and what we should do if we are not. Our deepening involvement, and growing vulnerability in light of Brexit, makes this all the more important. The Rusi paper lays out useful principles. Improved knowledge of the terrain comes first. Transparency is essential and will not come from the Chinese side, so must be enforced here. Unity, within and between governments, is essential, though hard to establish. And potential dangers must be assessed, as well as existing problems. The report argues that it would be naive, or even irresponsible, to allow the Chinese telecoms giant Huawei to supply key elements of the UK’s superfast 5G network – in contrast to the judgment of security chiefs that the risk can be contained.

Most importantly, it urges a carefully plotted course between kneejerk rejection and instinctive compliance. Mr Williamson’s childish foot-stamping achieved nothing except to remind us of his leadership ambitions, and led predictably to the cancellation of trade talks. But treading too gingerly not only sells us short now but diminishes our power in the longer run. Mr Osborne’s “golden era” strategy of wooing Beijing was in large part a response to the diplomatic freeze that followed the Dalai Lama’s visits to the UK – a period in which trade in fact continued to grow. It meant a marked diminution in challenges over issues such as human rights. In asking ourselves what kind of relationship we want with China, we are asking ourselves what kind of country we want to be.