 Mackarness was also noted as an 'indefatigable' supporter of Irish Home Rule.In 1909, Mackarness told his constituency Liberal Association that “for private reasons” he did not intend to fight the next election.The seat reverted to the Conservatives by a wide margin, William Arthur Mount recording a majority of 2,358 over the new Liberal candidate, Thomas Hedderwick the former MP for Wick Burghs.