Daughter of the television writer Pat Dunlop, she began as a child actress in the seventies featuring in a BBC version of the classic A Little Princess and as Lydia Holly in the ITV adaptation of South Riding. Her transition to adult roles began by playing Lizzie Hexham in a BBC version of Charles Dickens' Our Mutual Friend in 1976 and featuring in the very first series of the long-running hospital drama Angels. In 2000, Lesley joined the cast of the ITV series Where the Heart Is playing Anna Kirkwall. She is currently playing Brenda Walker in the ITV soap opera Emmerdale.