In 1990, Schlesinger listed her earlier provincial stage work as: Listed London work included: Schlesinger made her National Theatre debut in 1988 as Grace Wellborn in Ben Jonson's Bartholomew Fair staged in the Olivier Theatre, followed in 1989 by her role as Jacinta in the Cottesloe revival of Lope de Vega's Fuenteovejuna.
In November 1989, again at the National, she played the title role in Steven Berkoff's symbolist stage adaptation of Oscar Wilde's Salome, a production which transferred to the Phoenix Theatre in January 1990.
According to critic Robert Tanitch, "Katharine Schlesinger mimed the dance of the seven veils and, without having taken anything off, persuaded a hushed audience that she was standing there totally naked.
"[3] In February 1991, at the Royal Court's Theatre Upstairs, Schlesinger took part in performances of selected plays in the Young Writers' Festival.
Schlesinger's audio work includes William Shakespeare's Love's Labour's Lost[4] and Henry VIII.