A dark lanthorn (lantern). An allusion to Guy Fawkes, a member of The Gun-Powder Plot of 1605. To “stow the guy” means to conceal the lanthorn.
The Gun-Powder Plot was the scheme to blow up Parliament and King James I on 5 November 1605. Robert Catesby, whose father had been persecuted by Queen Elizabeth I for refusing to conform to the Church of England, organized and led a group of provincial Catholics with plans to replace the country’s Protestant government with a Catholic one. The plotters rented a cellar that extended under the House of Lords. One of the conspirators, Guy Fawkes, deposited casks of gunpowder in the space.
A few days before the opening of Parliament, Lord Monteagle, a brother-in-law of one of the conspirators, received an anonymous letter which warned him to avoid Parliament on November 5. Monteagle warned government officials, and Fawkes and the gunpowder barrels were discovered in the cellar around midnight the day before the scheduled explosion. Under torture, Fawkes revealed the identities of his fellow plotters, and over the next several weeks, all were found. Those who survived discovery were put on trial, found guilty, and executed for treason.
Every November 5, Guy Fawkes Day is celebrated by burning Fawkes in effigy.