A charismatic voice, a contradictory man

Dylan Thomas: A New Life
By Andrew Lycett
Overlook, 434 pp., illustrated, $35

The audience entering Cambridge's Brattle Theatre in the winter of 1951 may well have had only cursory acquaintance with the work of the Welsh poet Dylan Thomas. Three years later, when he gave a virtuoso solo performance of his play for voices, ''Under Milk Wood," at the Fogg Museum, he was one of the best-known poets of his generation, a colossus in a scene including Eliot and Auden.

Thomas's literary reputation no longer seems as durable as it did in the immediate postwar years. Still, it has survived and deservedly so; he wrote eight or nine poems that seem destined to last. As with many romantic poets, his best work flowered early. Choosing him as a subject, however, the British biographer Andrew Lycett accepted a challenge in overabundance. Gielgud, Guinness, and Emlyn Williams played Thomas onstage; Sidney Michaels wrote a successful Broadway play; Thomas is associated with New Directions Press and Caedmon (''A Child's Christmas in Wales") Records; the Sitwells' ''18 Poems" was only one of the ''lit mags" that influenced the poetry. Is there room for more? As is turned out there was. Perhaps the most interesting aspect is the biographer's capacity to find fresh meaning in a life that presumably has yielded every necessary interpretation.