The lady's bonnet was the basis for the sunbonnet or 'kappie'
worn by Dutch/Afrikaner women which evolved into a traditional
form of headgear - however, its origins were the English bonnet as seen here.
These fashions would have been in the forefront of trendiness when Natal's
settlers left England to journey to Natal ca late 1840s/50s. Their outfits were made
to last until completely outmoded, old gowns being unpicked and restitched, young boys' garments being cut down and made up to fit the child.
As to the gentleman's outfit, it would have been out of place for a farmer
in the Natal Midlands, who would wear drill trousers and calico shirt in the field, possibly with a straw sunhat.