Records of the Central Research Establishment are in HO 234, HO 235 and HO 236; of HM Inspectorate of Constabulary in HO 242; of the Police and Statistical Branch in HO 66; and of the Police Research and Planning Branch and successors in HO 222 and HO 377.
Annual police returns are in HO 63; police entry books are in HO 149; and symbol series files dealing with aspects of police work are in HO 287, HO 288, HO 310, HO 325 and HO 353.
Departmental Security Unit (DSU Symbol Series) files HO 483.
Police Liaison (PL Symbol Series) and Police Leadership and Powers (PLP Symbol Series) files HO 498.
Inspectorate of Constabularies (IC Symbol Series) files HO 504.
Support to Permanent Secretary and Home Office Board (CFP 7/3 Symbol Series) files HO 505.
Police National Computer (PNC Symbol) Series files HO 521.
Police and Crime Prevention (PCP Symbol Series) files HO 528.
Security Planning (SPL Symbol Series) files HO 532.