Stewart trained as an Accountant with the Birmingham firm of Farmiloe & Co. In 1976 he moved into industry on completion of his final exams as Group Accountant. Stewart was appointed to the main Board of Hadley Industries Holding Ltd in 1978 taking responsibility for the commercial and financial development of the Group. He completed the buy-out of the business from the Hadley family in April 2006 and is now the Group Chairman and Managing Director. Hadley have grown from £1 million annual turnover in the mid 1970’s to over £100 million annual turnover in 2012. Growth has been primarily by product development, not acquisition and Hadley now have manufacturing plants in the Middle East, Far East and Europe and licensees throughout the world.
Stewart was awarded the C.B.E. in the Queen's Birthday Honours List in June 2008 for services to industry in the West Midlands. He was appointed as Business in the Community's Regional Ambassador for the West Midlands by His Royal Highness, The Prince of Wales, 2007. He was appointed High Sheriff of the West Midlands in 2012 and Deputy Lieutenant, West Midlands 2013. He is a Patron of The Prince's Trust.
Stewart was formerly a Governor of the University of Wolverhampton. He was inaugurated as a Pro-Chancellor in September 2014 for a term of office until 3rd July 2019.