Our love for the Queen of Crime is undimmed. Another big-screen Poirot adaptation starring Kenneth Branagh’s preposterous moustache is coming this autumn, the BBC is dramatising Murder is Easy, and The Mousetrap continues its West End reign. But Lucy Bailey’s site-specific production of Agatha Christie play Witness for the Prosecution, which has been summoning audiences to London County Hall since 2017, has unique appeal: it’s not just a whodunit, but a wheredunit. 

Ralph Knott’s majestic Neo-Baroque chamber, once home to the Greater London Council and now standing in for the Old Bailey, is the star of the show. Its marble columns, red leather seats and vast vaulted ceiling dramatically elevate this 1953 courtroom drama (which Christie adapted from her 1925 short story). It lends grand solemnity to the proceedings and invites an immersed audience to cast their own judgements. You can even book seats in the jury box and deliver the verdict. 

On trial is cockney charmer Leonard Vole, who befriended a wealthy older woman, Emily French, and is now chief suspect in her brutal murder. His wife Romaine, a German actress he rescued from Berlin’s Russian sector, must confirm his alibi to save his neck – but can she be trusted? 

Christie’s suspicious view of human nature intersects brilliantly with the vagaries of the legal system in her Witness for the Prosecution play. The majority of the action takes place in the courtroom, and its inherent theatricality is dialled up to the max: costumes and wigs, exhibits held aloft like props, and competing florid barristers attempting to convince us that their story is the truth. 

Both the case and the plot hinge on assumptions, whether gender or class bias, or an aversion to outsiders (most jurors automatically believe a foreigner is lying, fears Vole’s QC). His declaration that “the system is only as robust as the people who uphold it” is a sobering point that still very much applies, while the judge’s exhortation to the jury to ignore prejudicial material in the press makes one think of the far greater difficulties now with social media.