Douglas was CEO of Tarsus Group, having joined the business when it launched in 1998, until Informa acquired it in April 2023 for approximately $1 billion. He previously held senior positions at Blenheim Group plc and, after its takeover, United Business Media plc. He is a former Chairman and Director of the Association of Event Organisers (AEO) and a former Chairman of the Events Industry Alliance. He is a board member of the US industry advocacy body, the Exhibition & Conference Alliance (ECA), and was also the first international board member of the US industry trade body, SISO, where he later served as Chair.

He is currently the Chairman of Cuil Bay Capital and Raccoon Media Group, and the Deputy Chairman of Jacobs Media. He also chairs the Trustees of the Green Hub Charity for Teens and the Cuil Bay Foundation.