Mackinnon's poetry is modest, meditative, without hyperbole or rhetoric. Critics have identified the influence of the American poet Robert Lowell in Mackinnon's first two collections, Monterey Cypress and The Coast of Bohemia, published within three years of one another. His latest collection, The Jupiter Collisions, is threaded together by two sequence-poems and provides retrospective contemplation of the author's childhood and adolescence, both in personal details and in the context of the 'Sixties (rock music, space travel, Minimalist art). The collection also affords a small number of poems in sonnet form, despite the poet's tendency towards vers-libre, thereby combining the legacy of Lowell with that of Auden.