Jim Semlyen | Managing Director

Jim’s journey in IT began with the Sinclair ZX81, sparking a passion that has spanned over four decades. His career started at Oxford University’s Physical Chemistry Laboratory, programming a room-sized mainframe for quantum behaviour simulations. He later pursued a study of robotic vision systems at the University of York’s Advanced Computer Architecture Group.

Jim’s expertise expanded into education technology, setting up early Windows networks and pioneering internet connections in York’s schools. By the mid-1990s, he transitioned to web development as Computing Officer for the University of York’s Department of Economics and Related Studies, where he created systems for staff, students, and research units.

In 2003, Jim launched his career as a freelance consultant in 2005 and co-founded Castlegate IT soon after. Under his leadership, Castlegate has grown into a trusted partner for organisations worldwide, delivering robust, high-performing websites. Jim’s focus on usability, accessibility, digital inclusion, and standards compliance ensures that every project maximises user engagement and conversion rates.