Edward D. Mitchell was a heraldry expert.
In 1887 Mitchell, of the College of Heralds at Queen Victoria Street, helped JW with designs for the royal coat of arms for the newly appointed Royal Society of British Artists. He made sure that JW's designs conformed to the rules of heraldry (#02128). He also did the lettering for memorial presented to the Queen (see (a) Monogram 'VR'; (b) Address to Queen Victoria; (c) Royal Coat of Arms (M.1132)).
MacDonald, Margaret F., James McNeill Whistler. Drawings, Pastels and Watercolours. A Catalogue Raisonné, New Haven and London, 1995.