Max Dupain's portrait of Jean Lorraine, a favourite model among Sydney’s artists and photographers of the 1930s and 1940s, graces the elegant cover of Paul Dalgarno’s Prudish Nation. All that gives a somewhat misleading impression of the nature of this book. It is not a work of history. Nor is it an investigation of whether Australia is a notably prudish nation. The variety of gender and sexual identities examined certainly does not leave an impression of prudishness. If Australia was once prudish, it is obviously less so now.

The Scottish-born Paul Dalgarno is himself polyamorous, and much – although by no means all – of the book is devoted to exploring this phenomenon. Dalgarno draws on his own experience with his wife, Jess, and partner, Kate, as well as his and Jess’s young sons. As Dalgarno explains, it can make for awkward moments in filling out the census, and pangs of embarrassment when being invited to events that allow for a ‘plus one’.

None of this will strike most readers as among the most onerous of oppressions or urgent of problems facing the world. Indeed, it might well seem an elaborate rationalisation for sexual selfishness: one partner is not enough, so let’s have two. But Dalgarno emphasises that he is discussing ‘consensual nonmonogamy’, not faithlessness. He explores the obvious objections and pitfalls, such as the management of jealousy and impact on children. He is defensive rather than fervent, thoughtful rather than sophistic – and when he infrequently veers towards the latter, one senses that he is mainly trying to convince himself rather than us.