The actor has already completed filming on ITV drama The Lady but revealed she will no longer promote the project following the emergence of an email sent by Sarah Ferguson to Jeffrey Epstein.
The Duchess described Epstein, a former financier and child sex offender, as a "steadfast, generous and supreme friend" to her in an email sent in April 2011, which only recently became public.
"Since completing the project, new information has come to light that makes it impossible for me to reconcile my values with Sarah Ferguson's behaviour, which I believe is inexcusable," Dormer told The Telegraph.
"For that reason, I will not be taking part in the promotion of the project. In keeping with my commitment to the wellbeing of children.
"I have donated my entire salary from this project to the National Association for People Abused in Childhood (NAPAC) and the Centre of Expertise on Child Sexual Abuse."
Ferguson's spokesperson has insisted that she only wrote the email because Epstein had threatened to sue her.
The Lady follows the downfall of Fergie's dresser Jane Andrews, who was jailed in 2001 for murdering her partner Tom Cressman at their flat in Fulham, west London, in 2000.
The official synopsis for the series reads: "Once a young working-class girl from Grimsby, Jane answered an advertisement in the magazine The Lady and to the astonishment of her friends and family, became the Duchess of York's dresser at Buckingham Palace."
"Moving amongst the highest social circles in Britain, Jane managed to secure a place in the upper-classes, only to lose her job with the Duchess after nine years of service.
"Still reeling from her fall from grace, Jane went on to meet charismatic businessman Thomas Cressman and fell deeply in love. Soon cracks began to develop in the romance Jane had pinned all her hopes on, with disastrous consequences."
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