Poet and playwright Tony Harrison sometimes seems a contradictory figure. Defiantly proud of his northern, working-class roots, he¡¯s also a classicist who wrote a magnificent verse translation of the Oresteia, and reconstructed an obscure and fragmentary Greek Satyr play for the National Theatre.

An atheist, he also beautifully adapted the Medieval Mystery Plays, and caused a storm on Channel 4 for ¡°profane¡± language in V, a poem about the desecration of his parents¡¯ grave.

His work is human, but always on an epic scale. No surprise, then, that his latest play turns out to be a defence of poetry and the word, told through a feat of physical endurance ¡ª Fridtjof Nansen¡¯s 1895 expedition to the North Pole.

Nansen travelled, initially in the ship Fram (¡°forward¡± in his native Norwegian), then by kayak and foot, to the northernmost point then reached. He and his travelling companion, the heavy-drinking cynic Johansen, were fundamentally incompatible but regularly shared a fur sleeping bag during their three-year trek.

Johansen would later commit suicide after another polar expedition with Roald Amundsen, while Nansen distinguished himself in the fields of science, politics and charity ¡ª enlisting famous names such as Sybil Thorndike and Gilbert Murray in the relief of Russian famine victims in the 1920s, and winning the Nobel Prize.

Jasper Britton, recently seen as John Gielgud in our own Nicholas de Jongh¡¯s play Plague Over England, stars as Nansen with Mark Addy as Johansen and Sian Thomas ¡ª Harrison¡¯s partner of 18 years ¡ª as Thorndike.

Harrison himself, who co-directs with designer Bob Crowley, says he intends to draw parallels with our age, not just in the area of celebrity appeals and the opposition between art and science, but in Nansen¡¯s belief that the world faced an ecological, albeit icy, apocalypse.

Oh, and the whole thing rhymes. Quite a challenge, especially in the unforgiving vastness of the Olivier. But Harrison is no stranger to this stage and his past work here has seen ambition pay off, and contradictions reconciled.

¡ö Previewing now and runs until 22 May. Information: 020 7452 3000, www.nationaltheatre.org.uk.