-only Rowling and 20 others — illustrators, editors and continuity experts — know the book's ending
-some employees had to work in near darkness to prevent them from reading the books
-The delivery trucks are fitted with satellite tracking systems GPS) costing up to £1,000 each
-written consent from Rowling's literary agent to read aloud from the book. Quizzes, riddles and crosswords are strictly banned.
Link to Original Source