where did the trial of lord george gordon happen?
Court of King's Bench
Trial of Lord George Gordon
The Trial of Lord George Gordon for high treason occurred on 5 February 1781 before Lord Mansfield in the Court of King's Bench, as a result of Gordon's role in the eponymously named riots. 
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Trial of Lord George Gordon [SEP] Introduction
The Trial of Lord George Gordon for high treason occurred on 5 February 1781 before Lord Mansfield in the Court of King's Bench, as a result of Gordon's role in the eponymously named riots. Gordon, President of the Protestant Association, had led a protest against the Papists Act 1778, a Catholic relief bill. Intending only to hand in a petition to Parliament, Gordon riled the crowd by announcing the postponement of the petition, denouncing Members of Parliament and launching "anti-Catholic harangues". The crowd of protesters fragmented and began looting nearby buildings; by the time the riots had finished a week later, 300 had died, and more property had been damaged than during the entire French Revolution.