The British stock-market crash that began after the collapse of Overend, Gurney was the Panic of 1866.
Overend, Gurney and Company had been a major London discount house, but it failed on May 10, 1866. Its collapse triggered a banking panic, a run on other institutions, and a sharp contraction in credit. The Bank of England eventually used its lender-of-last-resort powers to stabilize the financial system.
The panic affected Britain and spread financial stress internationally, although its causes included broader railway speculation and fragile credit structures. Overend, Gurney was not a conventional commercial bank in the modern sense; it was a powerful financial intermediary. The event helped shape later debates about central-bank support during crises.