Who owned the undercroft leased by the Gunpowder Plot conspirators?

The undercroft leased by the Gunpowder Plot conspirators was owned by John Whynniard.

Whynniard owned a building within the Palace of Westminster, close to the House of Lords. Its undercroft lay directly beneath the chamber where Parliament was due to meet, making it an ideal place to hide gunpowder and other supplies.

The conspirators acquired the lease on 25 March 1605. Thomas Percy arranged the tenancy, while Guy Fawkes—using the name John Johnson—posed as his servant and took responsibility for the building. The plotters eventually stored 36 barrels of gunpowder there.

A common mix-up is to credit Henry Ferrers, because Ferrers owned a nearby property and was Whynniard’s tenant. Dudley Carleton and John Hippisley helped arrange the property through the Earl of Northumberland’s agents, but neither owned the undercroft. The famous tunnel story is also misleading: historians have found no physical evidence that the conspirators actually dug one.