then a pioneering female palaeobotanist, published a book that would transform her life and many others. Married Love was a popular marriage guide and sex manual that advocated for marriages grounded in mutual affection, and expressed in mutual sexual pleasure; it aimed to combat sexual ignorance in marrying couples. In particular, it propounded theories about female sexual desire – women’s ‘primitive sex tides’ – which Stopes argued couples needed to understand in order to achieve ‘union with another soul, and the perfecting of oneself which such union brings’.

The book was a runaway success, being continually reprinted, and launching Stopes’ new career as a sexologist and birth control advocate. Thousands of women and men wrote to Stopes after its publication asking for advice. As Hera Cook argues, it isof cataclysmic events such as the First and Second World Wars or the abdication crisis.

The five decades between the First World War and women’s liberation saw profound changes in understandings, expectations and usages of love and romance. In 1918 Marie Stopes prophesied the dawning of a new era of mutual love, in which heterosexual couples would be awakened to ‘a new and unprecedented creation … the super-physical entity created by the perfect union in love of man and woman’. Her vision of modern Married Love became widely idealized in novels, psychology, the state-sponsored (and Catholic) marriage guidance movement and even in the Church of England’s marriage service.

As the contributors to our book show, however, this distinctive nexus of sex, love and romance had always only been an ideal.