[2] Mostyn was elected on November 7, 2016, defeating high profile, three-term incumbent and Yukon Party Deputy Premier Elaine Taylor by just 22 votes.
Throughout his career, he covered small business, politics, health, energy, technology, mining, the environment, and the arts.
His career as a journalist spanned the administrations of Yukon Premiers Tony Penikett, John Ostashek, Piers McDonald, Pat Duncan, Dennis Fentie and Darrell Pasloski.
[6] In the course of his career, he was published in The Globe and Mail, National Post, Vancouver Sun, and Up Here Magazine, and appeared on CBC Radio and TV and the BBC World Service.
[7] After leaving journalism in 2011, Mostyn worked for the Canadian Parks and Wilderness Society and its campaign to champion the Peel Watershed land-use plan.