The increasing use of black and Asian actors has led some in British theatre to congratulate themselves on the growing diversity of the British stage.

But experts have warned that casting ethnic minority actors without paying attention to the way they are lit, or what colour costumes they wear, puts them at a disadvantage to white performers.

An academic at London’s Globe Theatre says that black and Asian actors can be obscured by the dark costumes and furnishings and gloomy lighting traditionally associated with the staging of works by Shakespeare and other period dramatists.

Producers are now being urged to pay more attention to the set design, lighting and costume used in plays featuring ethnic minority actors, in order for the audience to get the most out of their performances.

Dr Farah Karim-Cooper, the Head of Higher Education & Research at Shakespeare’s Globe, said: “Using the same lighting and stage design as you do for white actors puts actors of colour at a disadvantage. There is a danger with traditionally dark, tragic, stage settings, that actors of colour merge into the background."