This small gambrel-roofed building was attached to the back of the Nichols–Overing House in 1840, when it was moved there to replace an ell destroyed by fire. In 1971, the NRF moved it to the museum side of the property. Oral tradition has it located on the site in the 1700s and its frame is certainly 18th century. Since it is the kind of utilitarian structure that might have housed General Prescott’s guards during his occupation of the Nichols–Overing House, the second floor is furnished to tell this story.

The Guard House site represents the event for which Prescott Farm has been named (and called by locals for centuries,) the capture of British Army General Prescott in early July 1777. General Prescott had, against the guidance of his advisers, moved his headquarters out of downtown Newport and into the country to the Nichols-Overing House. When word reached Patriot commander Lt. Col. William Barton of Prescott's vulnerability in the country he undertook a kidnapping mission to capture the British General and exchange him for captured Patriot General Lee. The victory was one of the first for the patriots in the American Revolution. Today the NRF uses the first floor for a variety of educational programs.