[4] He made his stage debut at the Schauspielhaus in October 1930 in the play Das kluge Kind directed by Max Reinhardt.

[1][4] Upon Haggard's return to the United Kingdom in 1931, his career path was initially discouraging: he received only small parts in various London plays and worked in repertory in Worthing.

[1] He undertook further study at the Royal Academy of Dramatic Art[4] and subsequently received good notices when he played Silvius in Shakespeare's As You Like It in London in 1933.

[4] He was noticed by the playwright Clemence Dane and made his first appearance in New York in 1934 as the poet Thomas Chatterton in her play Come of Age.

[1][4] Returning to Britain, he had successful roles in a number of plays, including Flowers of the Forest, a production of Mazo de la Roche's Whiteoaks, and he appeared as Konstantin in Chekhov's The Seagull,[4][5] and was hailed as one of the most promising and handsome classical actors of the era.

[6][14] While in the Middle East, Haggard fell in love with a beautiful Egyptian married woman whose husband worked in Palestine.