Main Library was part of the Great Court buildings designed by Hennessy and Hennessy in 1935-1936. It consisted of two floors with a glass ceiling in the light well in the centre. Main Building was designed to be extended with an additional three floors, with high ceilings and a large light well in the centre. When the Library had insufficient space for students and books it was decided to go ahead with the extension of three more floors, as specified by Hennessy and Hennessy. Birrell proposed five additional floors instead of the three, the installation of passenger lifts, fluorescent lighting, and air-conditioning. Birrell was responsible for the internal arrangement and finishes. This file comprises 15 plans for alterations and additions to Main Library. Includes: sketch of lower ground floor (now Level 1), working drawings for 1st to 5th floors (now Level 3 to Level 7), stair details and compactus shelving.

Main Library was later known as Undergraduate Library; with the construction of Central Library in 1971 its name was changed to Duhig Building; and later, around 2000, to Duhig Tower.

There are two architectural drawings, ink on paper, with the title The Union which may form part of the pilot plans for an extension to The Union Building which Birrell designed in 1962. There are 14 drawings for the Master Planning Report upon the Student Union Precinct University of Queensland, which was produced by Birrell and assistant architect Richard Stringer. This report was submitted to the Buildings and Grounds Committee in March 1966. 12 of these 14 drawings have the University of Queensland title block with J.P. Birrell as University Architect. Included with these drawings, which form part of the master plan for the precinct, are several designs for a Union Theatre. There are two pencil drawings related to the Union Theatre, without title, date, or creators. All plans are undated.