He was engaged by the Oxford Players, where he worked with the likes of John Gielgud and Robert Morley. As Napier recalled, his “ridiculously tall” 6’ 6” height played a crucial part in his securing the position and also almost losing it. J. B. Fagan had dismissed Tyrone Guthrie because he was too tall for most parts. Napier was interviewed (and accepted) as Guthrie's replacement while sitting down. Fagan realized that Napier was even taller than Guthrie when he stood up, but honoured his commitment. Napier performed for ten years (1929–1939) on the West End stage. Napier described himself as having a particular affinity for the work of George Bernard Shaw, and in 1937 appeared in a London revival of "Heartbreak House" supervised by Shaw himself.