In 1962 she played the flirtatious Natalia Snevellicci in the Bristol première of "Step into the Limelight", a musical by Edgar K. Bruce and Betty Lawrence based on the Crummles theatrical troupe in Charles Dickens' novel "Nicholas Nickleby". In 2004 a compact disc was released of "demo" recordings made at the time by members of the cast, with Lawrence on piano, together with ones cut in 1969 when the show was revived in Bristol with a new cast that included Josephine Gordon and Elric Cooper. Lewis appeared also at other provincial theatres: for example, with Robert Beatty, Kynaston Reeves and Geoffrey Palmer in George Ross and Campbell Singer's "Difference of Opinion" at the Theatre Royal, Brighton in 1965. She returned to the West End in 1963 for the London première of Leonard Bernstein's "On the Town" at the Prince of Wales Theatre. In a short run, Lewis took the feisty role of Claire (the part played by Ann Miller in the 1949 film and on Broadway by the show's librettist Betty Comden) alongside two American actresses, Andrea Jaffe and Carol Arthur. One view of Lewis's stage persona in the late '50s and early '60s is that she, Susan Hampshire and Anna Dawson, who all had leading roles in Slade musicals, "possessed an extraordinary Englishness of feature and bearing and voice that seems absolutely to have vanished from the theatre, perhaps from the world itself". In the mid '60s Gillian Lewis appeared in episodes of such popular television series as "Gideon's Way" (1964), "The Avengers" (1965), "Mogul" (1965), "Public Eye" (1965) and "The Baron" (1966). A number of her roles, then and later, were in series that subsequently acquired "cult" status among devotees. In the "Avengers" episode, "The Man-Eater of Surrey Green" (broadcast December 1965), she played Laura Burford, an old friend of Emma Peel (Diana Rigg) who was mysteriously lured away from scientific work alongside her tactile fiancé to a horticultural project aimed at propagating menacing bean-like plants with gigantic tendrils. As Joyce Grant in "The Baron" ("So Dark the Night", broadcast 15 March 1967), her father died in a spooky country house just before the series' eponymous hero (Steve Forrest as John Mannering) and his glamorous assistant (Sue Lloyd as Cordelia Winfield) arrived to value some antiques.