The Three Witches from Macbeth

Hey, it's Witchy Wednesday and I've got another striking art piece today.  A part of the National Portrait Gallery since 2011, this piece by Daniel Gardner was completed in 1775.  It is a gauche and chalk portrait simply entitled The Three Witches from Macbeth (Elizabeth Lamb, Viscountess of Melbourne; Georgiana, Duchess of Devonshire; Anne Seymour Damer).

According to the description provided by the National Portrait Gallery, the portrait features these three women who were very influential in society and Whig politics at the time, and who were all good friends.  It is believed that it was commissioned by Melbourne, and designed by either her or Damer.  Shakespearean scenes were rather in vogue and a contemporary interest in the supernatural made witches a favorite motif, however their depiction as the three weird sisters might have a deeper meaning...