William's debut feature film Lady Macbeth premiered at the Toronto International Film Festival, 2016. 

It was chosen as a Top Ten Pick of the festival by Variety and Rolling Stone and awarded the FIPRESCI International Critics' Prize at San Sebastian and Thessaloniki,

the Critics' Choice at Zurich and the Cineuropa Prize at Les Arcs, France.

 In 2013 his short film Best won the Sundance LondonShort Film Competition before screening at the Sundance Festival, 2014.

Previously he worked with film and video at art college before becoming a stage director.

As director-in-residence at the Young Vic Theatre, London he staged contemporary adaptations of European classics such as Ghosts by Ibsen, Kean by Sartre in Tokyo, Waiting For Godot in Munich and Shakespeare for the Royal Shakespeare Company's Complete Works Festival. His opera productions include Pergolesi in Portugal and Donizetti for ETO at Sadler's Wells, London.

BAFTAVariety and the Observer  have identified William as a director to watch.

He is represented by United Agents and WME.