In January 1873 he was again appointed part-time curator of the South African Museum in Cape Town, succeeding Edgar Leopold Layard.

[1] In July 1876 he was appointed full-time curator of the South African Museum in absentia as he had accompanied Premier John Charles Molteno to Britain and only returned in October of that year.

[1] Trimen studied Cape Lepidoptera in the years prior to his appointment as full-time curator of the South African Museum.

[1] Trimen received butterfly specimens from a network of friends including Bowker and his sister Mary Elizabeth Barber.

Triman was a member of the Vine Diseases Commission of 1880 and attended the international congress on Phylloxera in Bordeaux in 1881 on behalf of the Cape Colony.

[1] Trimen also described a new species of bird, the racket-tailed roller, based on skins provided to the South African Museum.