Born in Dublin, Ireland, Sheils began hairdressing in 2000 whilst studying Art and Design.
In 2002, after graduating with a National Diploma in Graphic Design, Sheils started his professional career at Toni & Guy in Dublin. He moved to London in 2003 and qualified as a stylist and colour technician at the Toni & Guy London Academy the following year. Sheils began teaching at Toni & Guy's New Oxford Street Academy in 2007, eventually becoming its Artist Director.
After moving into session work in 2010, Sheils worked as Sam McKnight's First Assistant for three years. Since then, Sheils has collaborated with the likes of Burberry, Chanel and Molly Goddard, and is now Creative Director of Chelsea Green Salon.