The announcement comes soon after the departure of MD Jo Birkin, as part of the firm's ongoing restructuring.
Richmond has been with Jumbo for almost three years, growing from National Account Manager to Sales Director. He will take full responsibility for the Jumbo Games business, and will be joined by a new Finance Manager soon.
In a statement, the firm said: "During his three years of co-operation we got to know Gray not only as a successful manager with strong growth potential but also as a very likeable colleague. Gray is committed to deliver the growth agenda of Jumbo Games, despite economic and exchange rate challenges. There is a very aggressive growth agenda for 2009 and Gray is very committed to deliver this."