China is to build a hidden chamber alongside Britain’s most sensitive communication cables as part of a network of 208 secret rooms beneath its new London “super-embassy”, The Telegraph can reveal. This newspaper has uncovered detailed plans for an underground complex below the vast diplomatic site in central London, which Beijing has sought to keep from public scrutiny. Despite the apparent security risk, Sir Keir Starmer is expected to approve the embassy before a visit to China later this month, when he is due to meet Xi Jinping, the Chinese president. The plans, which are redacted in all publicly available versions, can only be revealed because The Telegraph has uncovered the unredacted documents. The drawings show that a single concealed chamber will sit directly alongside fibre-optic cables transmitting financial data to the City of London, as well as email and messaging traffic for millions of internet users. The same hidden room is fitted with hot-air extraction systems, possibly suggesting the installation of heat-generating equipment such as advanced computers used for espionage. The plans also show …