In terms of academic and historical study the Civil Service is like a painting, a small part of which is brilliantly lit, but the rest barely perceived among the shadows. Great attention has been paid to the policy advice role played by senior ‘mandarins’, while the much vaster administrative and support functions underpinning the edifice remain largely ignored. Peter Hennessey's magisterial Whitehall has only two extremely incidental references to government libraries in over 850 pages. Not a single article on departmental libraries (which must be distinguished from the centrally funded ‘national libraries’) has appeared in the journal Library History. Until much more research is undertaken the conclusions and even some of the facts given below must remain rather tentative. There is at present little evidence on some important issues, such as the extent to which posts were professionalised before 1939 or the entry of women (who formed some 70% of professional staff by 1993) into government libraries.

Another major difficulty arises from the frequent reorganisation of Whitehall departments (e.g. the Ministry of Public Buildings and Works was renamed five times in thirty years) and their complex internal structures (thus the Ministry of Defence had some seventy individual libraries in the early 1990s). The sheer diversity of experience between government libraries thus prevents more than the crudest analytical generalisation in the space available. Likewise our evidence as to the deployment of technology and levels of service provision is often contradictory. For example, the Foreign Office (FO) librarian preferred to use a quill pen until his death in 1943, even though steel tipped ones had been available from the 1820s.