MacLean's many friends and visitors commented on his prodigious knowledge and deep interest in genealogy and local history. He continued to participate in left-wing politics, eventually joining the Scottish Labour Party. During his later years, he published few poems due to his "concern with quality and authenticity over quantity"; his family responsibilities and career left him little spare time to write. MacLean said that he had burned his poetry instead of publishing it because of his "long years of grinding school-teaching and addiction to an impossible lyric ideal".