It was owned by several wealthy men, including Sir Charles Pole and J. P. Morgan Jr. During World War I, a Voluntary Aid Detachment hospital was opened in the garage.

It later became a teacher training college and a residence of the University of Hertfordshire before being turned into flats, with the extensive grounds and parkland being used as a golf course.

[3] The house, which has an 18th-century core, was owned by Thomas Neate;[2] it was then bought and expanded in the gothic style for George Woodford Thelluson, a wealthy banker, and completed in 1802.

[2] During World War I, the hall provided support for wounded soldiers with a Voluntary Aid Detachment hospital being opened in the garage.

While based at Wall Hall, the selection process was made less subjective and psychologists were brought in to develop intelligence testing and extended interviews for officer candidates.

Agents were trained in various potential roles including parachuting, radio operation and weapons handling, along with propaganda in preparation for deployment in German-occupied Europe, particularly France, Netherlands and Belgium.

[2] The two-storey main house is built of brick with cement render and a slate roof hidden by a crenellated parapet.