Plenty of blame can be placed on the colonial powers of the day, not just Britain. Unfortunately for Africa, an awful lot of blame can also be placed on the first generation of post-independence leaders that has set the a pattern that continues to the present day. Without exception leaders like Nkrumah, Kenyatta, Nyerere and so on took power with sound motives only to build regimes that were dysfunctional, corrupt, nepotistic and unfailingly authoritarian. The often socialist systems they built lapsed into gangsterism that obeyed a single directive and that was to retain power at all costs. In many cases this meant exploiting tribal and racial differences, building huge networks of patronage and nepotism, enriching supporters and exploiting the rest of the population.
The following generations of leaders have been, if anything, worse. Seizing and keeping power by force and plundering their countries to boot. It could be argued that the likes of people like Mobutu, Amin, Bokassa and so on, men who bled their countries dry and whose policies led to poverty and war that continues today did way more harm then colonialism ever could have achieved.
Throw in under-development, lack of educational opportunities for Africans, Cold War power politics, ecological disasters, the IMF and Development Bank newly independent states in Africa were always destined to fail.