Some months ago there was a documentary on UK TV - the name of which now escapes me. It included, among some very thorough investigation into Oswald's background, a computerised 3-D construction of the motorcade minutes, second by second, using very sophisticated software techniques. It analysed the bullet trajectories and the sounds in minute detail.

The conclusion: that Lee Harvey Oswald was a mentally tormented, would-be defector to the USSR - a loner who was rejected by the USSR and, on his return to the US, was filled with a desire to prove himself to the Russians and make an impact by killing the President. His US Marine record proved that he was an excellent and trained marksman - more than capable of firing accurate shots in a short period of time. The detailed computer analysis of the Zapruder film is a model of clarity.

But people do love conspiracies. We have our own conspiracy-theorists over here, with the death of Princess Diana - who died because her chauffeur was drunk.