BANBURY, a little English town best known for a walk-on part in a nursery rhyme and as the eponymous origin of a fruitcake, is an unlikely fulcrum for the balance of power in the world of telecoms. But the “Cyber Security Evaluation Centre” set up there by Huawei, a Chinese telecoms giant, in 2010 marks a new way of persuading purchasers, and the British government, that equipment from the manufacturer that runs it can be trusted. It operates in close co-operation with GCHQ, Britain’s signals-intelligence agency, located conveniently just over the Cotswolds in Cheltenham. Its security-cleared staff, some of whom used to work for GCHQ, are responsible for making sure that the networking equipment and software that the Chinese firm wishes to sell to British telecoms companies are reliable, will only do what customers want them to do and cannot be exploited by cybercriminals or foreign spies—including Chinese ones.