> If the relationships were that mutually beneficial there’d be no reason for them to look to Russia or China after all that time.

The relationships aren't mutally beneficial anymore. One of the major reasons is that the public opinion in France (and by extension the French government) has become much more sensitive to issues of corruption and sustainable development. There were many awful things that French companies and African elites did in the past that went with the blessing of the French government. Some African regimes miss that blessed period and just want a "protector" which would fund their lavish lifestyles and help them keep the power, but without imposing their ethics. That's why they don't go with Germany either, or Japan, even though Germany has no recent history with Africa and Japan never had, and both would be ideal candidates as healthier alternatives to France and the UK.