The dark cloud over Britain will not return. We certainly need have no fear of travelling by train, Tube or bus in London or any other city.'Seven years later and Andrew Aitken re-reads the newspaper cutting he tore out and kept. The focus of most policing and security recently has been the London Olympics; but not for Aitken. For him, there is a puzzle to unravel whose roots pre-date the 1948 London Olympics.