In East Africa, Tanganyika (as a League of Nations mandate) supplemented existing colonies including Kenya and Uganda to form an extensive East Africa Protectorate. Parts of Cameroon and Togo were added to a West African empire based on Nigeria and the Gold Coast. White settlement in the East and West African empires was small. Along with the dual mandate, colonial administrations supposedly exercised trusteeship to protect the interests of Africans.
Inter-war colonial policy on East Africa was concerned with trusteeship, to protect African interests and constitutional arrangements. In Kenya a small but significant number of colonists settled in the cooler 'white highlands' around Nairobi. Indian immigrants, largely working as traders, also formed a coherent grouping in Kenya. To advance their political and economic position the colonists were aggressive at the expense of Africans, and campaigned for Crown colony status to strengthen their role in government. This was achieved in 1920 and the colonists, under the leadership of Lord Delamere, made plans for self-government, colliding with the political aspirations of Indian colonists.
In a declaration by the colonial secretary, Lord Devonshire, the British denied colonists self-government, asserting the paramount importance of African interests. The government did, however, protect colonists against competition from Indian traders. Devonshire intended to carry out the principle of trusteeship, to uphold the interests of Africans.
In 1927 a White Paper written by the Colonial Secretary, Leo Amery, argued in favour of sharing trusteeship with colonists and promoting their interests. He also suggested the possible federation of the East African colonies. In 1929 a Royal Commission under Sir Edward Hilton Young reverted to the 1923 declaration, ruling out self-government and federation in favour of a policy of trusteeship.
In 1931 Lord Passfield considered constitutional arrangements in East Africa and argued in favour of a dual mandate to reconcile colonist and African interests. He also argued for a common voters' roll based on educational qualification.
In the context of post-war economic crisis, by promoting economic development, Britain attempted to link its African colonies to economic reconstruction. Seen as having potential for agricultural development, East Africa was a major target. Cabinet discussed a development programme for Kenya as early as 1923. The Colonial Development Act of 1929 (the first of several) made provision for the funding of development projects in African colonies, but their usefulness was limited by low funding.
The Second World War increased British commitment to the economic development of the African Empire. The Colonial Welfare and Development Act of 1940 brought to an end colonial self-sufficiency and acknowledged the need for development funds. Wartime conditions produced an acute shortage of finance, but in 1945 a further act made substantial amounts for development available.
Development schemes, however, were sometimes inappropriate or unsuccessful. The Tanganyikan groundnut scheme from 1948 became a prime example of failed colonial development intervention.