11. IOR/R/20/B/2377-2653 Reference (shelfmark): IOR/R/20/B/2377-2653 Title: Chief Secretary: Secret and Top Secret files Collection Area: India Office Records and Private Papers Languages: English Date Range: 1941-1952 Extent: 267 files
12. IOR/R/20/B/2654-2679 Reference (shelfmark): IOR/R/20/B/2654-2679 Title: Chief Secretary: Secret Protectorate files Collection Area: India Office Records and Private Papers Languages: English Date Range: 1944-1955 Extent: 128 files
13. IOR/R/20/B/2680-2683 Reference (shelfmark): IOR/R/20/B/2680-2683 Title: Chief Secretary: Temporary secret files Collection Area: India Office Records and Private Papers Languages: English Date Range: 1951-1958 Extent: 4 files
14. IOR/R/20/B/2684-2780 Reference (shelfmark): IOR/R/20/B/2684-2780 Title: Chief Secretary: Ordinary files relating to the Eastern Aden Protecorate, Western Aden Protectorate and Kamaran Collection Area: India Office Records and Private Papers Languages: English Date Range: 1957-1964 Extent: 96 files
15. IOR/R/20/B/2781-3382 Reference (shelfmark): IOR/R/20/B/2781-3382 Title: Chief Secretary: Secret files Collection Area: India Office Records and Private Papers Languages: English Date Range: 1958-1964 Extent: 602 files
16. IOR/R/20/B/3383-3444 Reference (shelfmark): IOR/R/20/B/3383-3444 Title: Chief Secretary: Secret Annexe files Collection Area: India Office Records and Private Papers Languages: English Date Range: 1958-1965 Extent: 62 files
17. IOR/R/20/B/3445-3459 Reference (shelfmark): IOR/R/20/B/3445-3459 Title: Chief Secretary: Ordinary files Collection Area: India Office Records and Private Papers Languages: English Date Range: 1960-1965 Extent: 15 files