Teresa Palmer is an Australian actress known for her roles in various films and TV shows. However, as of my knowledge cutoff in September 2021, there is no specific information available about teresa palmer a discovery of witches grey trench coat in the TV series "A Discovery of Witches." It's possible that this reference is from a more recent development or a fictional scenario."A Discovery of Witches" is a television series based on the book of the same name by Deborah Harkness. It features a story involving witches, vampires, and demons. While characters in the series may wear various costumes and coats, I couldn't find any specific details about Teresa Palmer's character wearing a grey trench coat.