1. Philip Clarke - Tesco CIO to CEO
Featured in the 2008 edition of the CIO 100, Philip Clarke started at Tesco as a 14-year-old shelf stacker before re-joining the supermarket chain as a graduate trainee. Clarke became a Tesco board director in 1998, taking responsibility for the company's supply chain with tech responsibility coming a year later. Clarke became Chief Executive in 2011 and stepped down from the role in 2014 following a profit warning.