She is depicted by Reynolds as Euphrosyne, the Classical goddess of joy and one of the Three Graces.

Though unusual for a portrait of this period, Mary is depicted in dancing motion, stepping forward with her right leg and using her left arm to balance. She is positioned off-centre in the canvas and her swinging dress is cropped, adding to a sense of movement. Mary is also located in an open glade with windswept hair, creating a sense of wildness and spontaneity.

As befits the decorative theme of the Music Room (where this portrait is located), music is suggested by the several children shown behind Mary, each playing musical instruments. One child stares directly out of the canvas, telling the viewer to ‘shush’.

These elements of dance and music reflect the Three Graces’ mythological role in organising dances and festivals, as well as the domestic sociability expected of Mary herself.

For the composition of this portrait, Reynolds took inspiration from the French Old Master, Nicolas Poussin, with the figures around Mary arranged in a tumbling, triangular shape, with many arms and legs leading the viewer’s eye around the painting.