By the most extraordinary coincidence - Ripple Effect says it is a billion-to-one chance - there was a mock terrorist exercise going on in London that day. This was revealed by the organiser and former Scotland Yard officer Peter Power on BBC Radio 5 in the early evening after the atrocity.

He said: 'At half-past nine this morning we were running an exercise for a company of over a thousand people in London based on simultaneous bombs going off precisely at the railway stations where it happened this morning, so I still have the hairs on the back of my neck standing up.'

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