Yes, the play had the same name, and sadly, Verity Bargate died at the age of 41, about forty years ago. That play would be an interesting and topical watch these days.
Yes, it was written by Verity somebody. She called one of the children Willow. It was also a book but I can't remember whether that was by Verity somebody (Bargate?) Or somebody else. Or perhaps she wrote the book and someone else wrote the play, can't quite remember.
Seventies or early eighties, by woman writer. About a mother pretending her toddler son is a girl. At the end she is on a train with the child dressed in a frilly white dress and bonnet. She is stopped by social workers as they get off at the station, and the child is taken from her. Anyone remember it?