In 1901, Trew was sentenced to twelve months' hard labour after he incited an anti-Catholic riot, and Sloan took over his Sunday afternoon speeches on the steps of Belfast Customs House.

Johnston, an evangelical Orangeman, was first elected in 1868, defeating a millowner as the candidate of the United Protestant Working Men's Association of Ulster.

[2] While he later sat unopposed as an official Conservative, he established a reputation as a supporter of labour protection, tenant right, the secret ballot and woman's suffrage[3][4][5] In the tradition of Johnston, the Belfast Protestant Association challenged the Conservative Unionist nominee for South Belfast, presenting Sloan in the August 1902 by-election as the democratic candidate.

While Sloan had signed the manifesto he, and the bulk of the membership, broke with Crawford as he moved progressively toward an embrace of Irish Home Rule.

[8] With the Independent Order, Sloan supported dock and linen-mill workers, led by the syndicalist James Larkin, in the great Belfast Lockout of 1907.