John, 64, remembers that "being friends with a woman only meant one thing. You'd have found it very hard persuading people that you were going out somewhere with a member of the opposite sex and that it was a platonic thing." Does he feel that he could go out alone with a woman other than his wife? "No, that would be strange. I wouldn't know what to say."
Platonic relationships have had a bad press. They are so named not because Plato was too much of a dog for anyone to have fancied, but because of his theory that the soul's intellect and will could control its appetites and desires, the philosopher used the term to describe the non-sexual love between Socrates and the young male companions with whom he conducted Socratic dialogues long into the night. The Athenians didn't quite swallow this, and made him drink hemlock for his trouble. The same is true today: rather than suggesting refined meetings of like minds, the platonic relationship is tabloidese for alleged celebrity tonsil-tickling - viz "Will Carling and Princess Diana insist their relationship is platonic"; or for something much more bizarre and inexplicable - viz "Olivia Newton-John and Cliff Richard insist their relationship is platonic".
Out in the real world, it seems that heterosexual women and men are starting to enjoy each other's company without the addition of any physical incentive. "I find it very difficult to be intimate with my male friends," confesses Alex, 25. "They've all been brainwashed into living life like one long Martin Clunes impersonation. There's only a certain amount of territory you can cover if the conversation is limited to which Spice Girl you'd like to have over the sofa and what lager gets you pissed the quickest."
He's exaggerating, surely? "Well, yes, probably," he admits. "But there's so much less self-consciousness in a male-female friendship, and the range of things you can discuss with them - or admit to them - is much wider. And, of course, a slight element of flirtation helps a bit, too. Oils the wheels, especially in the office."
Flirtation, eh? Sounds like there is something stirring under Plato's toga. Are these new friendships just a way of combining being sensitive with going after the birds? Is Alex simply a male version of the eyelash-batting exponents of the so-called Fluffy Manifesto? "No, I don't think so. That idea's just the bimbo's last gasp. Just because there's an element of flirtation doesn't mean that me and my female friends are leading each other on. It's not as conscious as that."
Helen, 22, would agree. "That sort of constant flirtation is marvellous because it's so safe. Friends of different sexes usually fancy each other at some point, but it rarely coincides. When it does it tends to be a disaster." Men make easy friends and colleagues for Helen for precisely the same reason that they jar with Alex. "It's much easier to have friendships with men because you can talk to them without having to get really involved with them," she argues. "Women always want to talk to you about their abortions and their terrible sexual experiences, and unless I want to get to know them very well I don't really want to hear about that."
Catherine, 23, also finds men easier to get to know. "With men there's always a bit of flirtation going on, so it's more easy to get talking to them." There are pitfalls: three close male friends with whom she thought she was having a platonic relationship have tried to push matters in a carnal direction. "It was disappointing and upsetting, but I think I can see the signs of that now and stop it before it goes too far."
And while her close male friendships have sometimes gone awry in this way, she's certain that women and men are getting better at the platonic thing: "It always assumed that men only talked to women if they thought they were in with a chance of getting them into bed. When I'm at my parents' home and a male friend rings up for me, my mum always says, `Oh, you're being so naive, they only want to get into your pants'. It's all changed."
It's one of the less publicised effects of the transformation of our traditional gender roles, and things have clearly shifted gear rather recently. In 1989's When Harry Met Sally, Billy Crystal tells Meg Ryan that "men and women can't be friends because the sex part always gets in the way. No man can be friends with a woman he finds attractive." In 1997, it looks like they're managing it. Women and men are finding that they have to discover ways of communicating in contexts and places where they never used to meet: the office, the playgroup, the House of Commons. Unless you're an anchorite nun or a barman at the MCC pavilion, it's very hard to move in a gender-segregated professional or social world.
Professor Theodore Zeldin, whose Intimate History Of Humanity made him the touchy-feely prophet of a future of growing, sophisticated dialogue between individuals, contends that "conversation between men and women has barely begun". Now, more than at any other time, they're being forced to make friends with each other. And they're finding that they've got quite a lot to talk about.