A tree on Ancestry has the Humphreys family on ,( owner is a Gary Humphries ) with Charles Thomas Humphreys born 1883 in Farnham Surrey as is Arthur , Charles is in Shropshire in 1901, and ten years later in the Military, dying in Panteg in1953 There's no 1891 census mentioned on the tree,
Maybe Arthur stayed in SA when the family returned to UK, and so is absent on1901 census?