The show is apparently planned to hit the London stage in early 2013; Staunton described the switch from Sweeney Todd as "as a whole different ballgame" and the part of Rose as "a daunting role, a very American character."
Staunton, who described herself as "e-mail buddies" with Stephen Sondheim, has also clocked musical credits from Sondheim favourite Into The Woods, Guys And Dolls, and plays including Uncle Vanya and Entertaining Mr Sloane.
She has also performed on screen in the Harry Potter films as well as Shakespeare in Love, Sense and Sensibility and Much Ado About Nothing. She won a BAFTA in 2004 for her performance in Vera Drake.
Sondheim's Gypsy first opened on Broadway in 1959, and has been revived in 1974, 1989 and, 2003. A performance at the Curve Theatre in Leicester also opened earlier this year.