She continued: “It was almost not eating. I cannot and will not do that to myself again. It was in my own head.
“I was going on with this most beautiful woman who I always admired, Darcey Bussell, and she was so slender and tall, so graceful.
“She seemed everything I wasn’t.”
Although Darcey, who left the show in 2018, was “lovely and really encouraging”, Shirley dropped to a size six as she nearly stopped eating.