Last Wednesday Arnold was giving a talk on how to handle a terrorist incident, drawing on his experience covering Northern Ireland as a journalist for the BBC in the 1980s.
Arnold says the sceptical executives in his audience were unimpressed by his attempts to get them to imagine a terrorist incident in their area and by warnings that whenever he gives his talk 'things have a habit of happening'.
PRWeek might similarly have recoiled from the hard sell had Arnold's talk not taken place at the Tortworth Court hotel outside Gloucester. Within hours of Arnold's prophecy, police were storming a house in the city and are now holding a man under the Terrorism Act.
Arnold worries that his reputation as a jinx may precede him, remembering that a similar talk in the Midlands was quickly followed by a train derailment.
'I am supposed to meet a Georgian government minister on Saturday,' said Arnold. 'I will be waiting to see whether he turns up.'