HOL/1/2/1 "Tractive Force and Adhesion of Locomotives", by Harold Holcroft, read at The Institution of Locomotive Inspectors and Foremen

HOL/1/2/2 "The Fairlie Locomotive; part 2: later designs and productions", by the late P. C. Dewhurst, prepared by Harold Holcroft from accumulated notes, read at The Newcomen Society.

HOL/1/2/3 "Basic Facts concerning the First Newcomen Engine to be set at work" by Harold Holcroft

HOL/1/2/4 "Reflections upon the Position of Newcomen in 1712" by Harold Holcroft

HOL/1/2/5 "Design in Railway Engineering" by Harold Holcroft, read at Harwell Reactor School, Atomic Energy Research Establishment

HOL/1/2/6 "The Steam Locomotive - An Historial Review" by Harold Holcroft with a contibution by Mr J. Jones, read at The Institution of Mechanical Engineers; East Midlands Branch; Graduates and Students Section

HOL/1/3/1 "Three-Cylinder Locomotives" by Harold Holcroft

HOL/1/3/2 Bundle regarding the newspaper article entitled "The Liverpool and Manchester Railway" by Harold Holcroft

HOL/1/3/3 "Conjugated Valve Gears for Locomotives: Their History and Development" by Harold Holcroft

HOL/2/1/1 Notebook containing reference tables and diagrams relating to Great Western Railway, such as maximum load gauge and standard track layouts.

HOL/2/1/2 Notebook entitled "Notes on Reinforced Concrete"

HOL/2/1/3 Notebook entitled "Notes on Graphic Statics"

HOL/2/1/4 Harold Holcroft's notebooks used during his time at Great Western Railway.

HOL/2/1/5 Folder containing plans from Harold Holcroft's time at Great Western Railway

HOL/2/2/1 Set of notebooks containing field notes on locomotive trials at South Eastern and Chatham Railway

HOL/2/2/2 Booklet containing power charts for N and E1 class engines, decorated with Holcroft's doodles on the inside of the covers

HOL/2/2/3 Harold Holcroft's notebooks used during his time at South Eastern and Chatham Railway.

HOL/2/2/4 Sets of cards depicting steam chest pressure charts

HOL/2/2/5 Set of folders with notes relating to Oil Fuel and Steaming trials

HOL/2/3/1 Notebook containing information about running restrictions on the newly formed Southern Railway network

HOL/2/3/2 Plans and documents relating to the instalation and trialing of Anderson steam conservation equipment on the N-Class A816 locomotive

HOL/2/3/3 Harold Holcroft's notebooks used during his time at Southern Railway.

HOL/5/1/1 Letters from Oliver Bulleid to Harold Holcroft

HOL/5/1/2 Draft copies of letters from Harold Holcroft to Oliver Bulleid, as well as a draft of a letter to Bulleid's wife upon learning of his death, and her reply