I received this from a South Africa contact (she had no info on the Tathams as such).......:
It is a watercolor painted by Robert Bristow Tatham, spouse of Susan Noon (sister of Adolphus). It appears that he was well known for his artistic talents in the Durban area and this painting is in the collection of the Old Court House Museum, Durban. It's official title is: The Opening of the Natal Railway Company's Durban to Point Line, 26 June 1860. The scene depicts the ceremony marking this auspicious occasion - the first railway line to be opened in South Africa.The Royal D'Urban Rangers, mounted and dressed "up to the gutters" can be seen on the left. His Excellency the Lt. Governor Major Williamson, the Bishop Colenso, the Mayors of Durban and Pietermaritzburg, Members of the Natal Legislative Council and their ladies and other notables are seen on the platform. After Bishop Colenso had blessed the enterprise, the Governor took his place in the 1st class carriage while other guests travelled in the goods truck, suitably decorated for the day.