Nunns' book on Jeremy Corbyn’s rise to the leadership of the Labour Party, The Candidate: Jeremy Corbyn’s Improbable Path to Power, was first published in 2016. It won the 2017 Bread and Roses Award. Robert Potts in The Times Literary Supplement praised the book as a "very well-researched narrative" that was "widely sourced", commenting that “The story of how such an other-worldly figure became leader of the party simply by being himself is an oddly electrifying one”. Stephen Bush of the New Statesman wrote that "Corbyn is at last given a wholly sympathetic hearing", the work being "the most authoritative yet published on his rise", but criticised it for a "lack of fluency around the animating issues of the Labour right". Gaby Hinsliff, in The Guardian, included The Candidate in an article about the best books on politics of 2016.
