| Year | Play | Role | Theatre | Notes |
| 1952, 1954–55 | Babes in the Wood | Principal character | The Empire Theatre, Sheffield (1952) Derby Hippodrome Theatre (1954–55) | |
| 1957, 1959 | The Desert Song | Margot Bonvalet | His Majesty's Theatre, Aberdeen | 1967 studio recording |
| 1958–59 | Old Chelsea | Mary Fenton | King's Theatre, Glasgow | |
| 1960 | Camelot | Queen Guenevere | Majestic Theatre, Manhattan | Julie Andrews' understudy |
| 1962 | Lock Up Your Daughters | Cloris | Mermaid Theatre Her Majesty's Theatre | |
| 1963 | See You Inside | | Duchess Theatre | |
| 1963–64 | All in Love | Lydia Languish | Mayfair Theatre | Based on The Rivals by Richard Brinsley Sheridan |
| 1965 | Dearest Dracula | Lucy | Olympia Theatre, Dublin | |
| 1966 | Seven Brides for Seven Brothers | Milly | | 1966 recording |
| 1967–68, 1971 | Bless the Bride | | Richmond Theatre | 1967 studio recording |
| 1967 | Love From a Stranger | Cecily Harrington | Queen's Theatre, Hornchurch | |
| 1967 | Virtue in Danger | Berinthia | Queen's Theatre, Hornchurch | |
| 1968 | The Rivals | Lydia Languish | Queen's Theatre, Hornchurch | |
| 1969 | The Real Inspector Hound | Cynthia | Queen's Theatre, Hornchurch | |
| 1969 | Black Comedy | Clea | Queen's Theatre, Hornchurch | |
| 1969 | Ann Veronica | Ann Veronica Stanley | Cambridge Theatre | Cast recording |
| 1970 | Spider's Web | Clarissa Hailsham-Brown | Queen's Theatre, Hornchurch | |
| 1972 | Popkiss | Poppy Dickie | Globe Theatre Cambridge Arts Theatre | |
| 1973 | The Importance of Being Earnest | Honourable Gwendolen Fairfax | Queen's Theatre, Hornchurch | |
| 1975 | Small and Brassy | | King's Head Theatre Wyndham's Theatre | |
| 1978 | Lark Rise | Emma Timms | Royal National Theatre | |
| 1984 | Pack of Lies | Barbara Jackson | Lyric Theatre, London | Replacing Judi Dench |
| 1985, 1993–94 | Follies | Sally Durant Plummer | Forum Theatre, Wythenshawe Brighton Dome Haymarket Theatre | |
| 1986–90 | The Phantom of the Opera | Madame Giry | Her Majesty's Theatre | Leader of bible studies between shows, cast recording |
| 1993 | Jack and the Beanstalk | | | |
| 1995 | Snow White and the Seven Dwarfs | The Wicked Witch | | |
| 1996 | Follies: In Concert | | National Concert Hall, Dublin | |
| 1997–98 | Beauty and the Beast | Mrs Potts | Dominion Theatre | Cast recording |
| | Pal Joey | | | |
| | The King and I | Anna | Wolsey Theatre, Ipswich | |
| | The Mating Game | | | |
| | An Evening with Mary Millar | | | One-woman showTalking about her Christianity, life and work[citation needed] |