The US National Security Agency (NSA) tried to persuade its British counterpart to stop the Guardian publishing revelations about secret mass data collection from the NSA contractor, Edward Snowden. Sir Iain Lobban, the head of Government Communications Headquarters (GCHQ) ... rebuffed the suggestion that his agency should act as a censor on behalf of its US partner in electronic spying. British refusal to shut down publication of the leaks ... caused rifts within the Five Eyes signals intelligence coalition [according to] a new book ... by Richard Kerbaj. Kerbaj reports that the US-UK intelligence relationship was further strained when the head of the NSA, Gen Keith Alexander, failed to inform Lobban that the Americans had identified Snowden ... leaving the British agency investigating its own ranks in the search for the leaker. The Five Eyes allies were outraged that a contractor like Snowden, working as a computer systems administrator, could get access to their secrets, and that because of US government outsourcing, there were 1.5 million Americans with top security clearance like Snowden. Allies were not prepared to challenge the Americans out of anxiety that they could be cut off from the flow of intelligence. British officials also decided to bite their tongues ... because of the value of the intelligence and funding provided by the NSA. Sir Kim Darroch, the former UK national security adviser, is quoted ... saying: "The US give us more than we give them so we just have to basically get on with it."