In productions at the Royal Shakespeare Theatre, the Theatre Royal, Newcastle, and the Barbican Theatre in 1982–83, Armstrong played Trinculo in The Tempest and Petruchio in The Taming of the Shrew with Sinéad Cusack as Kate. In 1983, he played Ralph Trapdoor in The Roaring Girl starring Helen Mirren. He performed the roles of Leontes in The Winter's Tale and John Proctor in The Crucible on a national tour that included Christ Church, Spitalfields in 1984 and on tour to Poland in 1985. In 1985–86, he played Thersites in Troilus and Cressida.