[1] His most successful book, The Christmas Miracle of Jonathan Toomey by Susan Wojciechowski, has sold more than a million copies in the United States alone.
[3] He recalls that Belfast during The Troubles was a "scary" place for a teenager, and he used drawing and reading as a "way of escaping for a while from the horrors that were happening around me in the real world.
[23][24] In 2014, he won the Bisto Book of the Year Honour Award for Illustration for Mysterious Traveller by Mal Peet and Elspeth Graham.
[29][30][12] Lynch has worked in a number of areas other than illustrations for children's books, including creating posters for Opera Ireland[31] and for the Abbey Theatre's 2016 production of The Importance of Being Earnest.
[45] Despite not initially being interested in writing, Lynch has published two books: The Boy Who Fell Off the Mayflower, or John Howland's Good Fortune (2015) and The Haunted Lake (2020).
[11] They are typically colorful, detailed, and realistic,[47][15][10] and are lauded for their "exceptional range of texture and colour"[14] Each of Lynch's works begins with him reading and rereading the story until he gets a sense of what he wants to draw; he then produces rough sketches that he can later polish and turn into a final product.
[48][47] He tries to avoid using too many digital programs "in case they get too slick"[11] and, while he already has a distinctive, traditional style, he is open to trying new techniques such as the "charcoal and chalk rubbing" he did for The Boy Who Fell Off the Mayflower.
[8] For stories centering on humans, Lynch often relies on photographs and his actors wearing historically accurate garb to help visualise body language, but rarely uses this method when working with fairytales and folklore.
[8][49][48][10] Lynch was influenced by Arthur Rackham and Edmund Dulac in his early years, and later Maxfield Parrish, NC Wyeth, Norman Rockwell, Alan Lee, Gennady Spirin, and Brian Selznick.