According to Jaggard (1979), Vosper was heavily influenced by the political opinions and journalistic style of the Northern Miner's owner and editor, Thadeus O'Kane.
During the 1891 Australian shearers' strike he wrote an editorial entitled Bread or Blood in which he encouraged the strikers to resort to violence if peaceful means proved unsuccessful: "If your oppressors will not listen to reason let them feel cold lead and steel; as they have starved you, so do you shoot them."
"[1] A passionate supporter of trade unionism, Vosper became closely associated with the Labour movement, but was never a member of the Labor Party because he refused to take their pledge.
After working on Sydney and Melbourne newspapers for a short time, Vosper emigrated to Western Australia in 1892, just as the gold rushes were beginning.
[3] During 1895 Vosper edited the Geraldton Express for three months while its regular editor John Drew defended a libel action, and shortly afterwards served briefly as correspondent for the London-based West Australian Review.
In Coolgardie in December 1894, he established the Anti-Asiatic League, which aimed to maintain living standards by excluding "cheap coloured labour".
On 11 November 1897 he married a widow named Venetia Ann Nicholson, and shortly afterwards he used her capital to establish The Sunday Times.
In addition to working for these goals, Vosper also pushed for the construction of a railway between Esperance and Coolgardie, votes for women, and compulsory arbitration.
From May 1898, Vosper pushed for an inquiry into mental health policy and the treatment of female patients at the Fremantle Lunatic Asylum.
He argued that Western Australia should federate, but only after securing a guarantee that an intercontinental railway would be built at the cost of transport infrastructure.