When the Slavery Abolition Act was passed in 1833, it paid out the modern equivalent of billions in compensation — not to the 800,000 black men, women and children in their colonies, but to their disgruntled former owners. Instead of achieving instant liberty, the ex-slaves faced “apprenticeships”, working for seven years for the same men as before for low or no pay. These scandalous facts provide the material for this edifying new play by Juliet Gilkes Romero, which tracks the bill’s faltering progress. Outstanding among a gifted cast are Richard Clothier as an urbane reformist, Corey Montague-Sholay as a conflicted former slave, and Katherine Pearce as a clownish maid whose quirks help the expository medicine go down. A stirring score by Akintayo Akinbode, and compellingly unexpected moments, provide relief in what feels at times like a dramatised documentary, torn from the pages of Hansard. Nevertheless, as a corrective to Sceptred Isle versions of British history, The Whip cracks.