Rolf Tophoven, Director of the Terrorism Research Institute in Essen, Germany: “London is a centre of Islamist propaganda in Europe. There have been permanent, massive threats since the involvement of the British government in the Iraq war. Let’s not forget that the main enemy for the Islamists is the United States, and that’s not just since Sept 11, 2001 and Tony Blair is the closest ally of George W. Bush, so from that point of view it makes sense to hit the closest ally of the USA. This is another parallel with Madrid.”

Richard Clarke, on ABC’s Good Morning America: “This is a highly complex, coordinated attack. This is clearly in my mind related to the fact that the prime minister of the United Kingdom is at the other end of the country hosting the leaders of the industrial world. If it is Islamic terrorism — jihadist terrorism — they are sending a message that the leaders of the industrial world are being mocked and laid low by the jihadist terrorists.”