"If you agree to have sex on a presumption that you’re not going to get pregnant and told you can't get pregnant because the person’s had a vasectomy, and that’s a lie, it’s a deception and that is capable of being rape under the definition," Harriet Wistrich, a solicitor at the Centre for Women’s Justice, tells us. She is renowned for her work on cases such as the rejection of the release from prison of black cab rapist John Worboys.