The Bridgerton star posted the photo to her personal Instagram account, where she can be hiding behind tree branches.
Coughlan will play fairy Silky in the movie adaption of Enid Blyton’s children’s book, The Faraway Tree.
Speaking with The Hollywood Reporter, director Ben Gregor said: “She was absolutely amazing and was very passionate about doing it.”
“She’s an unbelievably perfect Silky.”
Describing Coughlan's whimsical character, Gregor said Silky is "basically the leader [of the group of the tree's inhabitants]".
"Moonface thinks he's the leader of the tree gang, but it's really Silky who runs it."
The film was written by Simon Farnaby, whose previous films include Wonka and Paddington 2.
The film’s star-studded cast includes Nicola Coughlan as Silky, Rebecca Ferguson as Dame Snap, Nonso Anozie as Moonface, Dustin Demri-Burns as the Saucepan Man, and Jessica Gunning as Dame Washalot.
It also stars Claire Foy and Andrew Garfield as Polly and Tim Thompson, the parents of the three protagonists, Beth, Joe and Fran, played by Delilah Bennett-Cardy, Phoenix Laroche and Billie Gadsdon.
A release date for The Magic Faraway Tree is yet to be announced.
