Old Bones Of The River which borrows liberally from Sanders Of The River, the film it satirizes finds Will Hay as a con man missionary going to take up the fabled white man's burden whether the natives want it or him. When the local colonial administrator succumbs to malaria, Hay becomes the man in charge even though he hasn't a clue what he's doing, no more than he did as a schoolteacher for the native kids. But it's a typical Will Hay character, blowhard to the extreme and if you don't what you're doing, fake it.
Second bananas Moore Marriott and Graham Moffatt are the captain and first mate of a tramp steamer, probably the African Queen before Humphrey Bogart took it over. Those two aren't much better at their jobs than Hay is with his. They find a baby abandoned in the bush and their attempts at caring for the toddler make those Three Godfathers look professional.
The final scene is these three doing a Beau Geste like last stand at the colonial fort which has been abandoned because of faulty instructions Hay gives in the first place. It works out better for them than it did for the Geste brothers.
In the Thirties there was a lot of sentiment growing for the United Kingdom to give up its colonial empire. The colonial service was a place to go for folks who couldn't get decent work in the mother country. It didn't always attract the best and brightest. More truth in this Will Hay comedy than some would care to admit. Interesting also that the location for this film is identified as the Gold Coast which became Ghana, the first area granted independence when the British started letting go of their colonies.
The film is a satire of some bad old days, but still fun.