Robertson's first professional employment was as a
cabaret dancer at London's
Savoy Hotel at the age of 16. Shortly afterward, she joined a dance group called The Go-Jo's, and a year later she became the lead singer and dancer of
BBC Two's
The Young Generation. Robertson's
West End career began with
A Little Night Music, directed by
Hal Prince, and the
revue Side By Side By Sondheim, which she subsequently took to
Toronto with
Georgia Brown. Other London theatre credits include
I Love My Wife,
My Fair Lady,
Jerome Kern Goes to Hollywood,
Song and Dance,
The Phantom of the Opera,
Love Never Dies, and
The Music Man. Robertson made her
Broadway debut in
Dance a Little Closer, the disastrous 1983 musical adaptation of ''
Idiot's Delight by Charles Strouse and her husband, Alan Jay Lerner, that closed on opening night. In 1986 she returned to Broadway with the Kern revue, which ran for 24 performances and proved to be her last Broadway appearance to date. She starred in an extensive US tour of The King and I'' and performed at the
Kennedy Center before
President Ronald Reagan and his wife, Nancy. She presented her one-woman show,
Just Liz, at the
Chichester Festival Theatre and the
Duke of York's Theatre in London. It later was taped and broadcast by
Television South. She is also a regular performer and part of the original cast of the touring play
Seven Deadly Sins Four Deadly Sinners. She starred in the musical
Hairspray at the
Shaftesbury Theatre, performing the role of 'Velma Von Tussle'. She played the Wicked Queen in the
Bristol Hippodrome Pantomime, Snow White from 11 December 2009, and the Fairy Godmother in Cinderella at the same for the Christmas 2013 run. She appeared as ‘Miss Smythe/Miss Andrew’ in the second London revival of
Mary Poppins at the
Prince Edward Theatre. The production reopened on the 7th of August 2021 after being closed due to the COVID-19 Pandemic, until its final show on 8 January 2023. == Charity work ==