Does seem strange, not least as many London based TANGOs rely on World Bank Funding. Do they look at organisational structure, staffing  and other stuff ?

Good point. Perhaps funders should ask whether just having white folk running all the NGOs might conceivably have a detrimental effect on organisations which work mainly with Africans. One of the things I've noticed is that they hire plenty of black folk on the ground, and as they're often the main or sometimes the only employers, there's a tendency for the folk on the ground to give a kind of racial cover to the white folk at the top - unsurprisingly espousing the views which originate with the people who pay them, then used to justify the views in a kind of opinion reverse engineering.