- 1Papers of Harold Holcroft (HOL)
26 May 1889 - 1 June 1983, fonds - 2Papers and articles (HOL/1)
16 May 1919 - 23 June 1972, series - 3Plans, drawings and notes (HOL/2)
c 1898 - 1946, series - 4Manuscript for unpublished book entitled "Life With Locos" (HOL/1/1)
? 1971 - 23 June 1972, file - 5Correspondence (HOL/5)
3 January 1919 - 9 May 1970, series - 6Photographs (HOL/6)
early 20th Century 1900-1924, series - 7Documents relating to the development of three-cylinder valve gears, collected by Harold Holcroft (HOL/1/4)
15 March 1949 - 18 January 1957, file - 8Patents (HOL/3)
25 October 1884 - 24 May 1928, series - 9Patent for "Improvements in or relating to valve gears for engines worked by fluid pressure" by Harold Holcroft (HOL/3/2)
2 April 1909, item - 10Patent for "Improved means for use in operating continuous brakes by a vacuum or compressed air" by Harold Holcroft (HOL/3/1)
23 December 1904, item - 11Copies of various specifications for patents relating to locomotive design (HOL/3/4)
25 October 1884 - 5 October 1921, file - 12Cuttings of articles written by Harold Holcroft for "The Engineer" (HOL/1/3)
16 May 1919 - 19 October 1951, file - 13Specification of patent for "Improvements in the Valve Gear of Three and Four-cylinder Locomotives" by Harold Holcroft (HOL/3/3)
28 February 1921, item - 14Set of notebooks containing field notes on locomotive trials at South Eastern and Chatham Railway (HOL/2/2/1)
10 May 1921 - 20 March 1925, file - 15Great Western Railway (HOL/2/1)
c 1898 – 1 May 1914, sub-series
