Napkins started being used in the Middle Ages. By the sixteenth century, napkins were placed over the left shoulder or arm.
"By the seventeenth century, the standard napkin was approximately 35 inches wide by 45 inches long." (http://www.foodreference.com/html/art-history-napkins-729.html)
I designed the blackwork embroidery pattern, with inspiration from 16th century Italian sampler at the V&A Museum for the flowers. The floral pattern can be found at:
Here are pictures of the napkin for Her Majesty from beginning to end:
Here are pictures of the napkin for His Majesty from beginning to end: