The University Registry guard books were assembled from the 1860s onwards to accommodate loose papers and are the precursors to modern subject files. They comprise documents of all kinds on every aspect of University administration; for example, accounting, professorships, degrees, University officers, property, Colleges, and relations with the town of Cambridge.
There are lists of the contents compiled by Registrary Luard (1862-91) and successors at the front of each volume. Titles are recorded as given on the spine of each volume. The contents of several guard books have been removed and reclassified, with the result that the following classmarks are no longer used: CUR 1, 40, 50.2-3, 66-66.3, 67, 74-5, 77-77.2, 101.1-4, 123-123.2, 127.