Kopal, NilsMakin, KatyWaldispühl, MichelleMegyesi, Beáta2024-05-082024-05-0820241736-6305https://hdl.handle.net/10062/98479https://doi.org/10.58009/aere-perennius0104This paper shows the decipherment of a 1724 encrypted letter, discovered recently in the Brougham Archive at University College London (UCL) Special Collections. The letter’s content hints at political intrigue and possibly relates to the Jacobite movement during George I’s reign in Great Britain. However, as all individuals mentioned in the letter are referred to bycode names, except for Madame de Prie, their true identities remain unknown to the authors. Therefore, any connection to the Jacobites remains speculative. The paper covers the cipher’s security, historical context, and unresolved inquiries surrounding the letter.enAttribution-NonCommercial-NoDerivatives 4.0 InternationalJacobite movementdeciphermenthistorical cryptologyUnited KingdomArticle