Pony's 'madam' was initially allowed monthly visitation following her rescue to "reduce the risk of retribution among villagers" who were angry about her being taken.
Michelle Desilets, who was director of the Borneo Orangutan Survival Foundation UK when Pony was rescued, says while Pony's case was very unique, local reaction to her rescue was not.
She said: "Pony was a cash cow and she earned that village a lot of money. The whole village was not willing to let her go.
"They wanted people coming in - in this case men from the fields - and spending their money.
"Pony's owner, the brothel madam, was screaming and screaming when we took her away.
"Everyone was upset. They really loved her in their own uninformed way.