Late 18th Century. England. Mounted Under Glass

This charming little oval frame from the late 18th century contains a portrait mounted under glass depicting two adorable children embracing. 
This highly virtuosic technique, developed as far back as antiquity, underwent significant development in the late 18th century.
The process was particularly popular in England, where it would later be mass-produced in the 1830s.
Here we are at the end of the 18th century; the object is still considered precious, as evidenced by the inventory labels on the back and the handwritten note indicating that it was given as a gift to a well-to-do family. 
The frame is made of carved wood gilded with gold leaf.
Everything is original; it has never been opened.
Very good condition