Years after standing out as the sister in Fleabag, Sian Clifford commands attention again as an artsy, unstable aristocrat hosting a film crew.

Isolated at her palatial English country house and seeking an audience for her outlandish new performance-installation work, Lady Isabella invites a young documentarian to make her –“aristocracy’s answer to the Kardashians” – better known. Seeing a rich cinematic subject in her delusions of grandeur, he allows himself and the film to sink ever deeper into her life – but keeping a safe distance from her soon proves difficult.

Writer-director Samuel Abrahams makes his feature debut with a sharp revival of the mockumentary, where riotously funny lines and situations seesaw against a more serious, unpredictable character drama. Clifford drives this as the immediately memorable Isabella, combining brilliant comic timing with a layered, moving character study.