The Medical School building is Prior’s largest work. Two of Prior’s former clients, Dr. Albutt and the Rev. J.B. Lock, were on the committee appointing the architect. Prior received an honorarium of only 100 guineas for the plans and elevations. He chose to adopt a classical idiom partly as a result of pressure from the committee.
The committee also influenced the design in other ways, such as insisting on a stone façade. In style, the building is based on English baroque, heavily influenced by recent buildings by architects such as Belcher, Pite and Blomfield. It also reflects the presence of J.J. Stephenson’s Chemical Laboratories (1886-8), immediately to the west of the site.
Many of Prior's domestic buildings had classical details, such as the Harrow Billiard Room. He also altered a number of 18th Century buildings, such as Downe Hall and High Grove. In 1895 he designed a cross for Sir Christopher Wren’s chapel at Pembroke College Cambridge and was impressed by "the genius of Wren."
The site is located on the corner of Downing Street and Corn Exchange Street. The building is basically L shaped in plan, with a long arm along Downing Street and the museum wing set at a skew. The Corn Exchange block widens from 42 to 70 feet (13m to m). The building was to be built in two phases, but the Corn Exchange block was not constructed until 1934.
The Downing Street elevation is three stories high, with three shallow bays with first floor oriels. The southeast and southwest bays have deep pediments, with the central bay having a triangular pediment. The basement forms a rusticated plinth, the front being battered and chamfered. The entrance is at the east end and is formed by a semi-circular arch with stepped windows above that light the stairwell. There are similar windows on the east elevation. There is a high parapet on the façade with the coat of arms of Professors Humphry and Clark. Lettering and a motto on the façade were cut by Eric Gill. The central gable is ornamented with carved lilies designed by Prior.
The rear elevation, again of three stories above a basement, had pairs of segmental headed separated by vertical panels of stone. It has now been built over.
The Downing Street front is of Ancaster stone with rusticated Derbyshire stone dressings. The northern rear elevation is in brick with stone dressings. The floors are of jointless cement, and the roof is supported by a rolled steel joist system. Prior paid great attention to the roof design to minimize potential dirt traps, ensuring that not even a rivet projected as a potential collecting area.
Prior designed the rolling stack book-shelving of the library, all the laboratory furniture, doors and fittings, and so on.