· Bolts from points 'lying next to track' · Former BBC chief among victims Vandalism has been identified as a possible cause of the Potters Bar rail crash, in which seven people died, senior rail industry sources told The Observer last night. A 'sophisticated' act of deliberate damage to a set of points outside the station could have caused the derailment, according to the sources. The revelation raised the prospect of a police murder or manslaughter inquiry into the tragedy. Experts inspecting the points after Friday's crash found that the nuts securing the control rod to the points had...