After the great success of my previous plea for help (thanks again, Lila), here is another flowering shrub. It had a heady fragrance and was growing by a dry river bed in SW Namibia in the Namib desert. I realize that it is another long-shot, but any help (even to family) would be greatly appreciated.
I think it is a Boscia sp. (flowers and leaves are similar to this one: Kyffhäuser flora - Boscia foetida subsp foetida)
Thank you Lila! Boscia seems to fit extremely well. What puzzles me a bit is that my notes suggest that the flowers had a pleasant aroma, descriptions of B. foetida don't seem to match that perception. But I can't find a closer match with other Boscia species, so perhaps the attractiveness of the scent is all down to the beholder! Thanks again for your great help.