During production of Series 16 (2012), Sharon Miller stepped down as head writer, and Andrew Brenner, who had written some "Thomas" stories in the third series, assumed the role after serving as script editor for "Blue Mountain Mystery". Additionally, Sam Barlow stepped down as story executive after the sixteenth series, and the production of the CGI animation was moved from Nitrogen Studios (of Vancouver) to Arc Productions (of Toronto). "King of the Railway" and Series 17, both released during 2013, serve as the first special and series developed by the new animation and production teams respectively.