Here is a buttons to wish for! The Tasmanian Main Line Company (T.M.L.) was a privately owned railway from 1872 to 1890. The company were the first railway between Hobart and Launceston. In 1890 the company was bought by the Government, and absorbed into the Tasmania Government Railways (1872-1978).
The Tasmania Transport Museum has kindly sent photos of uniforms and their GVI and ERII buttons. The buttons are all made by Stokes & Sons. They thought that all except that with the GVII buttons dated up to 1978 after which the railways were absorbed into the Australian National Railways Commission.