On 13 December 1867 its exercise yard was the target of a gunpowder explosion instigated by members of the Fenian Society in an attempt to aid the escape of Richard Burke , an arms supplier to the Fenians . The blast killed twelve bystanders and wounded 120 in Corporation Row ; and the event became known as the " Clerkenwell Outrage " . Some of those responsible were executed , with ringleader Michael Barrett becoming the last person to be publicly executed outside Newgate Prison
gunpowder explosion
Clerkenwell explosion
Clerkenwell Prison