Hat

I did my best to calm Tessa. Other executives sitting outside my office came to comfort her.

I couldn't resist going to the offices overlooking the Square to see for myself. I saw the hat, blown by a gust of wind, that of WPC Yvonne Fletcher, just 25 years old. A poignant sight - unforgettable. There it would stay.

Yvonne was taken to Westminster Hospital, fatally wounded... shot in the stomach by automatic gunfire from the embassy. Her fiancé, also a serving officer, had been by her side.

An hour later, she died. 10 others wounded too. The siege had begun.