When Mackenzie was first returned for Ross-shire in 1818 the Liverpool ministry, who remained neutral in the contest, considered him ‘a very uncertain card’; but he made a good impression as a conscientious Member and a ‘steady’ but ‘independent’ supporter of the government, which earned him a promise of their full backing for his re-election.
He presented a Ross-shire petition against the additional malt duty, 2 June 1820.
He could not consent to vote for any abstract proposition, or even for the matter of fact stated in the resolution ... knowing that it was to be followed by others intended to form the basis of practical measures
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He argued that these would not significantly increase the number of freeholders and would be ‘a direct violation of the Union’. He presented petitions against the Whig Kennedy’s Scottish juries bill, 18, 21 May 1821.
From this point Mackenzie’s attendance seems to have lapsed, although he was nominated to the select committee on Scottish turnpikes, 20 Mar. 1822. A sickly individual since boyhood, he was reported to have been ‘detained’ in Edinburgh ‘for six weeks by indisposition’ in mid-March 1822.
