The Ambassador Theatre Group (ATG) is a major international theatre organisation headquartered in the United Kingdom, with offices in Woking (head office), London, New York, Sydney, Mannheim and Cologne. ATG's key operations comprise three inter-related activities: theatre ownership and management, ticketing and marketing operations, and show productions The company was founded and run by the husband-and-wife team of Sir Howard Panter and Dame Rosemary Squire OBE, who topped The Stage 100 list of prominent UK theatre personalities from 2010 to 2016.