I watched a documentary recently about the 1916 film The Battle of the Somme, possibly the most successful British movies of all time; 20 million tickets were sold for it in Britain alone. The documentary featured attempts to work out which bits of the film were real and which bits were recreations. It was a silent movie but men could be seen talking. A lip reader was brought in and revealed what the men had said. Fascinating. But the scary bit came when experts in facial recognition were brought in to help identify some of the soldiers who appeared in the film. Stills from the movie were compared with photographs of people reputed to have been in it. On at least two occasions, the experts announced they had a close match, only for military records to reveal the man in the photograph could not be in the man in the film. What scared me was that these experts regularly gave evidence in court linking bad guys captured on security tapes to the accused. The experts were the first to admit that the identifications of the men in the movie were not definite, they would only go as far as to say it was worth looking at their military records. But they gave every appearance of knowing what they were talking about and if I were on a jury I would have taken their evidence far more seriously than I obviously should of. Sadly, I suspect few of the criminals fingered in court by "expert witnesses" of this kind had military records to back up their alibis.