Résumé
On Monday 30 April 2007, five men were convicted of terrorist offences relating to a plot to detonate a fertiliser bomb in the UK in 2004. The arrests were the result of a police and MI5 operation codenamed CREVICE. Following the trial, the media reported that at the time MI5 had been investigating CREVICE, the bomb plotters had been in contact with two unidentified men - now known to be Mohammed Siddique Khan and Shazad Tanweer - two of the four men who, on 7 July 2005, detonated bombs on the London transport system, killing 52 people and injuring several hundred others. This report investigates why MI5, knowing of Khan and Tanweer, did not prevent the 2005 bombings.