From now on, Comfort decided, it was going to be something more akin to a banquet. It was not to be regarded any more as a duty, a guilty secret, a quick one at the end of an evening, a stab in the dark or a silent embarrassment. He used to claim he was inspired by a woman patient who told him (in 1960) that she was appalled to be pregnant, because soon her neighbours would know that she and her husband had been getting up to dirty, sordid acts of darkness.The Joy of Sex set out to demystify love-making, but also to allow it to be regarded as something else: a recreation. His ideas about sexual liberation changed a lot in the 12 years of the book’s gestation, but at their core was a desire to remove decades-old accretions of guilt and shame from the business of sexual intercourse. It made you feel gob-smacked, intrigued and slightly repelled all at once, as you might have felt on walking into a room and finding your girlfriend’s mother and father on the sofa with nothing on.Oddly enough, that little domestic fantasy was quite close to what Dr Alex Comfort had in mind when he first came up with the concept of the book. Bloody hell, we thought, how can they just leave a volume called The Joy of Sex, containing actual drawings of people having oral sex, just lying about on this mild suburban coffee table, as if were one of those arty photographic books on Venetian masks or migrating birds? Such bizarre explicitness in the heart of the suburban Seventies. How we gawped, we teenagers, as we leafed through the pages in the living-rooms of our friends’ liberated parents.

The bearded Neanderthal and his silky-haired inamorata disported their naked selves through 200-odd pages of complicated sexual calisthenics and languorous flesh-devourings in gulp-inspiring close-up.
For the first time ever, the full lexicon of sexual possibility, the whole positional and directional compass of love-making, the actual what-goes-where machinery of engorged human interconnectedness was on spectacular physical display. They were clearly just about to kiss – but a feral, hungry quality about the man implied that something more fundamental was about to happen And in the book’s ensuing pages, something did. The cover showed a long-haired, Cro-Magnon roughneck with a black beard, tilting his face towards the face of an alarmed-looking brunette from a Modesty Blaise comic strip. That was when a strange book appeared on the coffee tables of the affluent British middle classes.

For Philip Larkin, sexual intercourse began in 1963; for the rest of us, sex only got seriously under way 30 years ago, in the summer of 1972. Enveloped in its climactic heart-warming vision of Irish brotherliness and belonging, you could quite forget that there’s an outfit called the IRA.To 27 July (020-7328 1000). But when the news of another UDA massacre adds a sobering touch to this wishful fantasy of escape, it merely serves to highlight other ways in which the piece is escapist. Maguire’s eruptively joyous solo turn conjures up an entire packed, electric New York bar and his display of good-humoured boozy camaraderie is undeniably infectious. This is pushed to the limit in the livelier second half, where our pen-pushing hero shocks himself by boarding a plane to the US and whooping it up with southern Irish fans as they watch the Republic’s victory over Italy. But, both in the writing and the actor’s cartoony impersonations, Kenneth’s narrow-minded wife and her friends are reduced to two-dimensional grotesques and the drama thereby diminished.The play engineers an increasingly simplistic contrast, symbolised by the difference between the lovely life-affirming disorder of his Catholic boss’s home and the defended, tidy sterility of his own hearth. Maguire’s barnstorming performance certainly communicates the tragicomic predicament of a man who can no longer fit into this pinched, would-be genteel world where the Hoover is regularly switched on to drown out any politics on the telly.