In these days of nationally televised sex in boxes, perhaps it's hard to conceive of a time when sex was considered an unsuitable topic for science. According to Masters of Sex, back in 1956 the only people brave enough to mount a serious study of the topic were Dr William Masters and his research assistant, Virginia Johnson.

In fact, Masters and Johnson weren't quite the pioneers that Channel 4's new period drama would have us believe. The sexologist Alfred Kinsey and his team at Indiana University had already published two taboo-breaking volumes on sexual behaviour – and Liam Neeson has already starred in a 2004 film about just that. If it's material for a TV adaptation you're after, however, the Masters and Johnson story has much more to recommend it. Not only is there the real-life slow-burning romance of the protagonists to explore (they eventually married in 1971), but while Kinsey's research was interview-based, Masters and Johnson actually persuaded hundreds of individuals to have sex, live in a laboratory, where they could be hooked up to machines and have their physical responses measured.

The presence of that redoubtable Welsh actor Michael Sheen in the title role kept us on the right side of respectability, while Lizzy Caplan (Janis the goth from Mean Girls) as Johnson had the mischievous smile necessary to set off his dourness. In this episode, Johnson's character not only gave Masters the benefit of a female perspective, but her failed attempt at forging a progressive sexual relationship with Master's colleague Dr Ethan Haas also placed the whole experiment within a social context. Haas's inability to accept women as individuals with their own desires ultimately led to a dramatic confrontation and a bloody nose for Johnson.

Of course, Mad Men has already explored similar territory with more elegance and subtlety, but while Matthew Weiner's drama inspires viewer nostalgia for smart dress codes and socially acceptable daytime drinking, the contemporary parallels in Masters of Sex are much more immediately obvious. Sex Box notwithstanding, we still live in a world where prudishness inhibits scientifically informed debate on topics such as internet pornography and school sex education. And as Johnson's experience illustrated, sexual liberation without the concurrent liberation of women is just so much masturbation in a box.