How far was British expansion in Africa in the years 1890 to 1914 driven primarily by strategic motives?

Before tackling the question: This question is an exercise in balancing the numerous factors that drove British expansion. Structurally, your essay should breakdown into sections evaluating the impact of different motives on expansion- the role of strategy should receive the most attention- by making reference to a wide variety of case studies across the African continent. A monocausal explanation will be entirely insufficient, and factors are frequently deeply interconnected. Your essay should recognise this, though it is easy to fall into the trap of using this as an excuse and failing to answer the question.
For: Many conquests were strategically aimed at protecting initial acquisitions and trading companies established beforehand- as existing conquests and economically valuable colonies (most notably Egypt and South Africa) came under threat, the government responded with military action and expansion. In the Sudan, the fear that the French or the Germans would cut off the headwaters of the Nile drove the invasion of the Mahidist state there, while the possibility of German support for the Boer states lead to tensions and eventual war- the British colonization of Bechuanaland (just before the period) was a clearly strategic settlement, cutting the Boers off from the Germans. In Ashantiland too the threat of raids motivated expansion. Economic value of the territories is not a key contributing factor- the actual economic value of conquered territories was very low and generally they were a financial burden to maintain as a result of the extreme costs of defence.
Against: The strategic risk was actually often quite small- the key role in accentuating it was actually played by party politics (the invasion of the Sudan was driven by a new Conservative government under Sailsbury) and dominant individuals (Rhodes, Milner and Lord Lugard). These individuals sometimes indirectly but often directly carried out imperial expansion- in Uganda (Lugard), Rhodesia (Rhodes), Sudan (Kitchener) and in the Boer War (Milner). An ideology of empire ('civilising mission') is another important element in motivating expansion- it furthermore plays a key role in motivating these individuals. Even though the actual economic value of these territories proves to be minimal, a faith in their perceived economic value could still be an important spur for expansion, especially for capitalists like Rhodes.
Conc- The role of strategy is important- it provided a key motivation for expansion and at times could directly lead to it (Bechuanaland). Compared to the economic value of the territories, for example, it is clearly a more important cause. However, in most cases expansion 'on the ground' was carried out by key individuals whose ambition drove an expansion that was not really strategically necessary. They were influences by a vast variety of factors of which strategic concerns were only really one- the role of these individuals is therefore much more important than that of strategy.