Local residents have voiced their anger over plans which could see one of Devon's most famous landmarks sold.
The house was modelled on the Palace of Versailles
Torbay Council is considering selling Oldway Mansion in Paignton, which it claims is too expensive to maintain.
A group opposed to the sale lobbied Mayor Nick Bye who hosted a forum at Oldway for directly-elected mayors.
It is thought Oldway Mansion could become a super casino if Torbay is successful in its bid, with takings used to help fund its upkeep.
The Casino Advisory Panel will reveal its chosen location for a regional casino on Tuesday, with Blackpool and Greenwich thought to be the frontrunners.
Oldway Mansion was bought by Isaac Merritt Singer, the founder of the sewing machine company in 1871.
It was rebuilt and extended but remained the Singer family home until the end of the World War I, when it was used as a hospital.
During World War II it became home to RAF cadets undergoing air crew training, after which is was sold to Torbay Borough Council for about £45,000.
But the increasing cost of maintenance has become a financial burden for the council and it has put out an informal invitation to tender to see if there is any private interest in running it.
Many local people do not want Oldway Mansion to become a casino
The house, modelled on the Palace of Versailles and set in 17 acres of formal gardens, was used for a film in 1968 about the life of dancer Isadora Duncan, starring Vanessa Redgrave.
In 2004, it doubled as Buckingham Palace in a film Churchill: The Hollywood Years, featuring Neve Campbell and Christian Slater.
But many residents do not want to see the house turned into a casino, arguing it was sold to the council for a reduced price on the understanding it would remain freely open to the public.