The manuscript had been stored for more than 60 years in a strong-room among miles of documents in the West Sussex Record Office, until its significance was revealed by two Harvard University researchers last year.
Today, Meghan Markle carried out five engagements in Sussex, visiting the county for the first time on official royal business.
Meghan was vocal in her interest and surprise at finding it in Sussex, saying: "My goodness, wow, what are the chances?"
Upon their arrival, the royal couple were greeted by Sussex locals including children from Westbourne House School who presented the pair with an A-Z guide of the area.
Meghan greeted one child who was held up to the barriers, while Harry patted the head of a baby. We said, "Welcome to Sussex", and she shook our hands. Not only is she handling her new royal life with grace and charm, she's also (well, most likely) maintaining her very thorough health and fitness routine - you can tell by the impressive definition of her upper arms.
Just after 2pm, Harry and Meghan will greet members of the public again as they arrive in Brighton.
Donning a light camel Armani coat layered over a dark green Hugo Boss pencil skirt and matching button-down green shirt by And Other Stories with nude Stuart Weitzman pumps, the former American actress was a bit reminiscent of her past Suits character Rachel Zane in her business casual ensemble.
In Brighton, after a tour of the Royal Pavilion, Harry and Meghan met volunteers and staff at the nearby Survivors' Network, a service that supports victims of sexual violence.