The fact that the wild, bloodied harangue to camera was delivered by a black man with no trace of a foreign accent – indeed, in an accent that seemed to originate in south London in particular – suggests homegrown militants, perhaps men radicalized via the Internet, through a form of widely dispersed propaganda rather than targeted brainwashing. …

The Cobra group will have to decide whether to raise the terrorist threat level from its present “substantial” to “critical.” Since there was no advance intelligence or “chatter” to indicate an attack, it is being described as a “lone wolf” operation and that, experts say, would not require raising the threat level. However, security around military bases in London was stepped up. …

The behavior of the attackers immediately after the killing suggests that they may have been waiting for the armed police to arrive with the idea of achieving a very public martyrdom by dying in a hail of bullets. Instead, as they face questioning in hospital they are the now the only people who can explain this gruesome atrocity.