He was elected to the Legislative Council of South Australia for the Central District in May 1900, serving until October 1906. Vardon resigned to contest the federal election in December 1906 as an Anti-Socialist candidate for the three South Australian seats in the Australian Senate. At the first count he was in fourth place, 16 votes behind Dugald Crosby. A second count however put Vardon into third, 34 votes ahead of Crosby. Justice Barton, sitting as the Court of Disputed Returns, found that 185 votes had been invalidated because of errors by the returning officers which affected the outcome of the election and declared the election void on 31 May 1907. The South Australian Labor Government attempted to install James O'Loghlin in the vacancy. Vardon's initial attempts to obtain a fresh election were unsuccessful. Vardon subsequently succeeded with the High Court declaring O'Loghlin's appointment was void and ordering a supplementary election. Vardon and O'Loghlin both contested the election, with Vardon winning comfortably with 54% of the vote. He was defeated in the 1913 Election, by now a member of the Commonwealth Liberal Party.
