Zentropa readies Danish director Nikolaj Arcel’s 18th century palace love story, which has been four years in preparation.

Danish actor Mads Mikkelsen, who has just finished UK director Paul Anderson’s new version of The Three Musketeers, will stay in the 18th century to play the lead in Danish director Nikolaj Arcel’s A Royal Affair, which will start shooting in March. Arcel has worked on the project since 2007.

Produced by Meta Louise Foldager and Sisse Graum Jørgensen for Zentropa Entertainments, Arcel’s fourth feature will co-star Swedish actress Alica Wikander, who was most recently in Pure and Ella Lemhagen’s The Crown Jewels (Kronjuvelerna), and was selected as an EFP Shooting Star at the Berlinale.

Foldager produced Lars von Trier’s Antichrist and is now finishing his Melancholia, while Jørgensen made Susanne Bier’s Golden Globe winner and Oscar-nominated In a Better World (Hævnen). The Danish Film Institute and Eurimages are both supporting the project, with $1.2m and $0.8m, respectively.

Penned with Rasmus Heisterberg, who co-wrote Arcel’s award-winning King’s Game (Kongekabale), A Royal Affair is the story of the love affair between German physician Johann Friedrich Struensee and Danish Queen Caroline Mathilde, an English princess who at 15 was married to Denmark’s King Christian VII.

In 1769 Struensee became the physician to the king, who suffered from schizophrenia, and he gained strong influence at court both because of his successful treatment and as the queen’s lover. Appointed cabinet minister in 1790, he had a hand in governing Denmark for 18 months.

Struensee issued in the region of 2,000 cabinet orders, introduced freedom of the press and abolised torture, but his reforming zeal, his nationality and his romantic liaison with the queen made him many enemies. In January 1772 he was brought down by a conspiracy. Accused of having usurped the king’s power, he was subsequently decapitated.

Described by Arcel as ”a great romantic love story, about forbidden love” involving a man ”who almost changed the course of history,” A Royal Affair will be ready for a spring 2012 premiere. Nordisk Film Distribution will release domestically, while TrustNordisk handles international sales.