Stewart commissioned into The Royal Regiment of Wales in 1994 and served in UK. Germany, Bosnia, Kosovo, Northern Ireland and two tours in Afghanistan. On 4 July 2009, Stewart was commanding B Company, 2 Mercian when shrapnel from an Improvised Explosive Device tore into his brain. Promoted to Lieutenant Colonel he was unable to take command of his Battalion due to his brain injury and was consequently medically discharged in March 2012. Stewart's brain impairments prevent him from holding down any form of regular employment.
Stewart took part in the original production of The Two World's of Charlie F in 2012 and the subsequent tour of Canada and England in 2014. This experience helped him regain his motivation, desire and appreciation of life. After taking up painting as a form of self-therapy, Stewart decided to begin a career as an artist. He has completed less than twenty paintings but won the Great Art prize at the 2015 Armed Forces Art Society exhibition at the Mall Galleries and recently the Sir John Stibbon prize as judged by Emma Stibbon RA at the Army Art Society 2015 exhibition. He is currently training with the artist Tim Wright, who taught Timothy Spall to paint for the film Mr Turner.
Stewart completed the 1000 mile Walk of Britain on behalf of the charity Walking With The Wounded in 2015. He had two poems published in Heroes: 100 Poems from the New Generation of War Poets, participates in educational workshops with the acting companies Charlie F and Combat Veteran Players. He finds the Arts magical, therapeutic and exciting. He was part of Gareth Malone’s choir which opened the Invictus games in 2016 and the Choir will be singing at this year’s BBC Sports Personality of the Year Award. No longer embarrassed by performing, Stewart even participated in a dance project which would have been unheard of before his injury.