This paper examines how links between the People's Republic of China and the UK were rebuilt in the 1970s. It not only fills a gap in the historiography but also makes three particular arguments. The first is that there were two intersecting institutional paths along which the rebuilding of links were followed: a foreign policy path, in which the most important body was the Foreign and Commonwealth Office, and an academy-level path in which relations between the Royal Society and the Chinese Academy of Sciences (also known in the early years as the Academia Sinica) were crucial. Especially under conditions in which access and travel to China were extremely restricted, the Royal Society acted as a ‘gatekeeper’, rationing visits to a select few researchers. The second argument is that science was a strategic pathfinder or diplomatic ‘avant garde’. The maintenance of scientific links, even during the most difficult periods of this history when they were all but severed, meant that a path was kept open to ‘further communication and exchange between peoples—and governments’, as Kathlin Smith has found in the broadly similar case of relations between China and the USA. In particular, scientific relations formed an important bridge in the negotiation and eventual agreement of the first treaty signed between the UK and communist China in 1978. It was no coincidence that this highest-level political agreement was accompanied by a parallel accord between the scientific academies. Third, I argue that, nevertheless, even this treaty was not entirely new, and that the model for the China–UK treaty was existing agreements on technology exchanges made with Eastern European countries.