The duty-free industry's most important annual trade show, the Tax Free World Association (TFWA) World Exhibition, celebrates its 25th anniversary in Cannes next week. This US$37bn global business has always prided itself on knowing how to throw a good party. But few heading to this year's show will be in the mood to celebrate the silver jubilee, despite the lavish dinner and rock concert which organiser TFWA has planned. Joe Bates reports.