New seating upholstery, carpets, a central projection screen and improved lighting systems are included in the refurbishment of the 300-capacity London theatre. Accessibility will also be enhanced.
The National Association of Local Councils annual conference and exhibition on 4-5 September is the first event scheduled to take place at the venue following the renovation.
The conference is anticipated to attract 250 delegates and the exhibition will comprise more than 25 stands.
Royal College of Physicians general manager of marketing and facilities Clive Ostler said: "The National Association of Local Councils event will not only see first use of the auditorium, but it will also demonstrate the versatility and scope of our range of meetings and exhibition space."