Within five years, the marriage was in trouble due to the couple's incompatibility and near 13-year age difference. In a videotape recorded by Peter Settelen in 1992, Diana admitted that by 1986, she had been "deeply in love with someone who worked in this environment." It is thought she was referring to Barry Mannakee, who was transferred to the Diplomatic Protection Squad in 1986 after his managers had determined that his relationship with Diana had been inappropriate. Diana later commenced a relationship with Major James Hewitt, the family's former riding instructor. Charles and Diana's evident discomfort in each other's company led to them being dubbed "The Glums" by the press. Diana exposed Charles's affair with Camilla in a book by Andrew Morton, "Diana, Her True Story". Audio tapes of her own extramarital flirtations also surfaced. Persistent suggestions that Hewitt is Prince Harry's father have been based on a physical similarity between Hewitt and Harry. However, Harry had already been born by the time Diana's affair with Hewitt began.