Greg Tiernan was the director of Thomas and Friends from 2009 to 2012. In the twelfth season, he worked as unit director for Nitrogen Studios. He began work directing the series after the CGI transition, taking over from Steve Asquith. He was replaced by David Baas when production was moved to Arc Productions in 2012. He is married to Nicole Stinn and has been working in the animation industry for twenty-seven years.