Soper was an alternate
Eliza Doolittle on the original UK tour of
My Fair Lady in 1965. She was later cast in the original 1971 London production of the musical
Godspell, alongside
Jeremy Irons,
David Essex,
Julie Covington and
Marti Webb. The production opened at
The Roundhouse,
Chalk Farm and later transferred to
Wyndhams Theatre. In 1974 she appeared as one of the two girlfriends in the original London production of the musical
Billy, with lyrics by
Don Black and music by
John Barry, based on the story of
Billy Liar. Billy was played by
Michael Crawford and the other girlfriend by
Elaine Paige. Her other theatre work includes the second production of
Good;
Mother Courage (
National Theatre); and
Sunday in the Park with George,
Jorrocks,
The Canterbury Tales,
Side by Side by Sondheim,
The Mitford Girls,
Les Misérables,
Which Witch, and
Salad Days (
West End). She was in the original cast of the 1970s musical
Betjemania based on the poems of
John Betjeman. In 2010, she appeared with
Opera della Luna as Little Buttercup in
Gilbert and Sullivan's
H.M.S. Pinafore. In 2011 at the Brighton Festival she played Rattigan’s mother Vera in
The Art of Concealment, a new play; and toured the UK as Norah in
Star Quality by
Noël Coward, as Matron in
Doctor In The House, as Verity Carr in
Morse, in
House of Ghosts, and as Helena in
Maurice’s Jubilee by Nichola MacAuliffe. She was Mrs Pearce in
My Fair Lady at Kilworth House Theatre, 2013; Gay later played Mrs Higgins in the musical on a tour of Denmark. At the
Birmingham Rep she was the Storyteller in Stiles and Drew’s new musical version of
Peter Pan, and Fraulein Schneider in
Cabaret at Frankfurt; played in
Cole in Hong Kong,
Betjemania and
Narnia in New York, and Ruth in
Blithe Spirit in Stockholm, and Cherry May Waterton in Coward's
Nude with Violin at the Royal Exchange Manchester for Marianne Elliott. In 2008, Soper performed the lead role of
Sister Wendy Beckett in
Postcards from God - The Sister Wendy Musical at Hackney Empire Studio and reprised the role for the concept cast recording in 2010. In 2012 she received plaudits for her performance in
The Busy Body at the
Southwark Playhouse in London. Soper appeared in the original production of
The Curious Incident of the Dog in the Night-Time at the
Gielgud Theatre in London. == Recorded musical career ==