For a moment, the nervous chatter, rustling costumes and jovial jostling came to a standstill. Silence fell over the 36,000 competitors who just minutes earlier had been impatiently rearranging themselves for the start of the London Marathon. For 30 aching seconds the spring sunshine beat down on their bowed heads, a sea of black ribbons pinned to their chests, as they remembered those who never got a chance to cross the finish line. It was a deeply tender and haunting image, and unlike anything ever seen in the 32-year-history of the race.