Brian Cox has signed on to a performance of Orson Welles’ unmade screenplay Heart of Darkness.

It’s a cause for celebration for Orson Welles fans — and Joseph Conrad fans. Artist Fiona Banner is presenting the first performance of Welles’ screenplay based on Conrad’s classic Heart Of Darkness.

Brian Cox will play all the parts in the special reading, planned for March 31 from 5:30 pm. The reading will be streamed live at www.aroomforlondon.co.uk (and available there through June 30) and also projected onto a screen in the Southbank Centre’s Purcell Room (free admittance).

Welles had adapted the story in the late 1930s and planned to play the roles of narrator Marlow and Kurtz. RKO decided not to make the film because it was too expensive and too political (Kurtz could be seen as a Hitler-like figure), so Welles made his debut with Citizen Kane instead.

Fiona Banner said: “Like the original novel, Welles’ script is a parody of power gone bad. It’s also a narrative of seduction, both a lens and a mirror. In the 1890s, Conrad’s theme was colonialism, in the 1930s Welles’ theme was the rise of fascism. Today, the focus is greed, globalisation and high finance.”

Cox will be performing the entire script live to camera in A Room For London, a boat-shaped installation at the top of Southbank Centre’s Queen Elizabeth Hall. The boat, called Roi des Belges, was designed by David Kohn Architects in collaboration with Banner, and was inspired by the riverboat of the same name captained by Conrad in the Congo in 1890.

The screenplay reading is part of Artangel’s A Room For London programme, which uses the boat as a temporary studio for writers, musicians and artists throughout 2012.