Greetham, who has been a non-executive director at the company since January 2002, said: "In two years' time Opex will be seen as a media service rather than an exhibition contractor. We will provide everything from laying carpet tiles to developing new media and technology strategies."
The company is about to buy an NEC-based contractor and a web development firm. A strategic review of Opex will be completed by the end of this month.
O'Connor is expected to remain at the company until the end of April.