• 1971
The Swahili Coast: Politics, Diplomacy and Trade on the East African Littoral, (Allen & Unwin) • 1981
Dictionary of Biography 1961–1970, with E.T. Williams (Oxford University Press) • 1986
Dictionary of Biography 1971–1980, with
Lord Blake(Oxford University Press) • 1990
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Dictionary of Biography 1986–1990, (Oxford University Press) • 1993
Dictionary of National Biography–Missing Persons, (Oxford University Press) • 1990
Power: A Political History, (Harrup, OUP and various) • 1985
Cataract, (with Philip Awdry) (Faber & Faber) • 1996
Hutchinson Encyclopedia of Biography (Helicon) • 1998
David Livingstone, (Sutton Publications) Written as part of a biographical series which Nicholls edited. • 2000
A History of St Anthony’s College 1950–2000, (Macmillan) • 2002
Elspeth Huxley: A Biography, (HarperCollins) (Thomas Dunne Books in USA). • 2005
Red Strangers: The White Tribe of Kenya, (Timewell Press) • 2011
A Kenya Childhood, (blurb.com) ==References==