|Architect||Edward William Godwin|
|Architectural style(s)||Gothic Revival style|
|Designated||19 January 1952|
The building which was designed by Edward William Godwin in the Gothic Revival style, was completed in 1864. The original part of the building was symmetrical with three first-floor windows either side of the main entrance. The building has a statue, designed by Sir Francis Chantrey of Spencer Perceval, Member of Parliament for Northampton and the only British Prime Minister to have been assassinated, which was unveiled in 1817.
The building was extended to the designs of A W Jeffrey and Matthew Holding in 1892. The walls of the Great Hall, which display images of famous local men, were decorated by Colin Gill in 1925. There are also murals of "The Muses Contemplating Northampton" which were painted by Henry Bird in 1949.
A plaque on the eastern extension marks the fact that Diana, Princess of Wales was made a Freeman of the Borough of Northampton in 1989, marking her and her family's strong connections with the town and with Althorp where she was brought up and is buried. The plaque below the memorial reads: "The memorial above was unveiled by the 9th Earl Spencer in memory of his sister, 7 November 2002 in the presence of the Mayor of Northampton, Michael Geoffrey Boss".