Let’s All Go Down the Strand began a prolonged period of success in London's West End, with Sheridan appearing in both comedic and dramatic roles for the next 25 years. She starred in Ronald Gow's A Boston Story (1968, opposite Tony Britton, Duchess Theatre); Ira Wallach's Out of the Question (1969, again opposite Dame Gladys Cooper, St Martin's Theatre), and in the title role of Ray Cooney's Move Over Mrs Markham (1972, again opposite Tony Britton, Vaudeville Theatre). She played the Countess of Chell in Waterhouse & Hall's The Card (1973, with Jim Dale, Queen's Theatre), and starred in Frances Durbridge's The Gentle Hook (1973, Yvonne Arnaud Theatre, Guildford, then Piccadilly Theatre), Samuel Taylor & Cornelia Otis Skinner's The Pleasure of His Company (1976 revival, starring opposite Douglas Fairbanks Jr, Phoenix Theatre), Agatha Christie's A Murder Is Announced (1977, opposite Dulcie Gray, Vaudeville Theatre), william Douglas Home's In The Red (1977, with Gerald Harper, Whitehall Theatre) and Noël Coward's Present Laughter (1981, with Donald Sinden and Gwen Watford, Vaudeville Theatre). The latter production was recorded and transmitted on BBC Television. During 1978/79, Dinah starred opposite John Gielgud in Half Life which toured the UK, before they both took the play to Toronto, Canada.