MI5 is much enhanced since Crevice: but it still can’t make guarantees

For almost two years, Westminster has been abuzz with what many MPs believed to be an explosive secret. The ringleader of the 7 July London bombings, Mohammed Sidique Khan, was not a so-called ‘clean skin’ who came out of the blue. Instead, he had been bugged, photographed and followed during an MI5 investigation into a thwarted fertiliser-bomb plot more than a year earlier. ‘When this gets out,’ one shadow minister told me last summer, ‘it could bring down the government.’

Well, it got out on Monday, when five men were sentenced to life over the fertiliser plot intercepted in what police called Operation Crevice in March 2004. Arguably, it was MI5’s greatest success — yet the next day’s headlines suggested precisely the reverse. The media were finally allowed to disclose the link between the Crevice investigation and the London bombings — and that Khan had slipped through MI5’s fingers, keeping his head down for a year or more before making his murderous comeback.