Prince Harry and Meghan Markle kept their relationship under wraps for months, knowing that everything would change as soon as their secret was out.
But despite their best efforts , the news was soon leaked and the couple had just a few hours to prepare before it made headline news.
In their new book Finding Freedom, which has been serialised by the Times ahead of its release next month, authors Omid Scobie and Carolyn Durand share details of what happened on the night the couple were told their game was up and how Meghan was so terrified, she called the police.
They write: "One night late in October in Toronto, Harry was happy, and so was Meghan. Until their received a call from one of Harry's aides at Kensington Palace. It wasn't good news.
"A tabloid was going to run with the story of their relationship. Their main worry was that her place would be besieged by photographers within 24 hours.
"They had little time to think, because there were only a couple of paparrazi in Toronto but it wouldn't be long before photographers flew in from New York and LA, all hoping to get that first picture of the happy couple."
The Duke was inundated with calls from his staff, many of them trying to get him to return to London early as they were concerned about his slimmed down security team.
However, he refused to leave.
Scobie and Durand claim that while Meghan was nervous about what was to come, she was also relieved as it meant she no longer had to lie to family and friends.
They say that she got more than 100 messages from former friends and acquaintances looking for gossip.
But the authors claim that the true extend of the fame that came with dating a royal was a huge shock to Meghan, and resulted in her sending one particularly worried message to a friend.
They write: "Prior to meeting Harry, the only times she experiences cameras were on a set or on a red carpet.
"The security was necessary. Shortly after the news broke, a photographer from an LA-based photo agency had scaled the fence into her back garden and waited for Meghan by her car, hoping to get a picture before she headed out to run errands.
"Meghan was terrified and called the police.
"'This is how it's always going to be, isn't it?', she said to a friend."
