Sarah Bly played the role of Jemima the kitten in the London premiere of "Cats". In the play, she sang the following songs: "Memory" in the second half of "The Moment Of Happiness" ”, “Skimbleshanks” (just the chorus) and “Memory”.

The song "Memory" appears three times in the play, the first time it is sung solo by Elaine Paige, and the second time is in the second half of "The Moment Of Happiness", by Sarah Brightman sang the lead and several other singers sang backup. The last appearance is near the end of the play, which is also the climax of the play. Memory appeared this time and Sarah Brightman sang the first few lines (a clearer voice, kitten), followed by Elaine Paige (old cat).

So Sarah Brightman is not the heroine of "Cats", nor is she the lead singer of "Memories", but she did participate in the London premiere (you can find in the DVD of "Cats" less than her), also sang part of "Memories". Of course, she later performed the song solo on the album and on multiple occasions, but that’s a story later.