For a start, one thing most people forget is that effective contraception existed for decades before the arrival of "the Pill". Jennifer Worth met a Boer War veteran who, once he left the army, decided that he wasn't going to inflict his wife with endless pregnancies, so after his two daughters were born, they always used contraception - I suspect condoms. Both Marie Stopes and Margaret Sanger were pushing intra-uterine devices. During the 1920s one of the fads of the avant garde was "companionate marriage", which might be defined as cohabitation with contraception, but without commitment. In 1927 Bertrand Russell was talking about developing a new sexual morality, a via media between monogamy and promiscuity, involving modern contraception. In 1943, C. S. Lewis stated: "Contraceptives have made sexual indulgence far less costly within marriage and far safer outside it than ever before." In his 1948 novel, The Haunting of Toby Jugg, Dennis Wheatley imagined a Satanic school where promiscuity was promoted, and all the girls were fitted with a contraceptive device. Yes, this might have been fantasy, but it described the accepted medical knowledge of the time.
Nevertheless, all this appears to have been the situation with the upper and middle classes - or at least sections of them. Mrs. Worth's war veteran notwithstanding, it doesn't appear to have percolated down to the lower classes. Just the same, I was a teenager when the oral contraceptive was introduced, and I can affirm that the male locker room conversation centred on "frenchies" ie condoms. Fellows were genuinely frightened of shotgun weddings. Also, they knew that even "easy" girls would become difficult if they weren't offered protection.
Now, if you were planning a career of sexual abandon, a condom has a lot going for it. Although not perfect, it is at least as effective as the pill. It needs only be used on the occasion, rather than every day. It also protects from venereal disease, which no pill could do. (That's another thing: female-based contraceptives are really only useful in monogamous relationships.) So why didn't the condom kick start the sexual revolution?
The immediate beneficiaries of the pill were married women. Single women did not rush out to acquire it - even assuming their doctors would prescribe it. Genuinely promiscuous women no doubt did, as did some of those with a regular boyfriend whom they hoped to marry. But otherwise, for her to seek the oral contraceptive would be to cross a psychological and sociological rubicon; it would mean that she was planning to be promiscuous. Likewise, a male seducer would tell her he had a condom; he wouldn't ask if she was on the pill. If she were, seduction would hardly be necessary; it was already established that she was "easy". But I was around in the "swinging sixties", and I can assure you, the "swinging" was honoured more in the breach than the observance. The moral law was still too deeply embedded.
What broke it down was, I would suggest, was really a series of actions by governments in the late 1960s and in the 1970s, when they really got underway. The first was the relaxation of censorship of obscenity. Dr. John Court was able to show that, in all western nations, there was a strong temporal relationship between the legalisation of pornography and a sudden increase in rape. But for our purposes, a major result was the normalisation of unchastity in films and literature. The next movement was the legalisation of abortion. You will, of course, remember that in the U.S. this was done by judicial decree, rather than through legislation by the democratically elected representatives. About this time, it was decided to introduce sex education into schools. While a good case could be made for this, the radicals turned it into a how-to-do-it course in unchastity. None of these changes had been made as the result of public pressure. By and large, most of society was against them, or at least neutral. They were pushed by a hard core of sexual radicals, and only after they had been well established did they gather mainstream acceptance. Culture, in this case, was downstream from the law.
The final step lay in paying an allowance to unmarried mothers, forgetting the basic economic rule that what you subsidise you get more of. Errant males could now do their thing without fear of paternity suits or shotgun weddings - even if they couldn't persuade their girlfriends to get an abortion. Marginalised girls found they could get government benefits, even a free house, by having an illegitimate child. I would suggest that when unmarried mothers on government assistance reached a certain critical level, the sexual revolution was complete.
Most of this had only a tenuous link to the oral contraceptive. Ironically, it took another decade for condoms to get back into fashion, and then only because a new and terrifying STD had arrived.