Semi-pornographic displays of lesbianism, performed by straight girls for straight boys, are ubiquitous.

Sooner or later, as Quentin Crisp once observed, everything deviant becomes mainstream. "In an expanding universe, time is on the side of the outcast," wrote the pink-haired, homosexual Englishman.

"Those who once inhabited the suburbs of human contempt find that without changing their address they eventually live in the metropolis."

Even Crisp, however, could not have anticipated the speed and suddenness with which lesbianism would be overtaken by popular culture. Only a decade or two ago, strange to recall, girl-on-girl action was still quite outré. In official quarters, especially the military, it was thought positively perilous.

Whitehall documents released last week show how seriously the armed forces took the threat of Sapphism. From 1950 until the 1990s, the Women's Royal Air Force used a secret surveillance list - or "lesbian index" - to keep track of women engaged in "suspected unnatural female friendships".

Airwomen caught canoodling faced instant dismissal - though squadron leaders reserved the right to distinguish between the "abnormal woman who enters the service already perverted" (a lost cause) and the young innocent who should be "given a chance to recover a normal life".

Civilian attitudes were hardly more enlightened. When I was at school in the 1980s, being a "lezza" was disastrously uncool, associated with hairy legs and games mistresses in hobnail boots.

One girl, a preternaturally tough and charismatic character, came out and got away with it, but her lovers (myself included) lived in constant terror of discovery.

In the playground - perhaps the only social arena more conservative than the army - the punishment for difference is social death.

Lipstick lesbians had not yet been invented, and it was not until years later, when I read Fanny Hill at university, that I realised some people - namely men - might be quite impressed by my Sapphic past.

The first man I told was struck dumb for several minutes, his jaw swinging loosely on its hinges, before recovering himself enough to ask, with a dreamy smile: "So what exactly do lesbians do together?"

How sweet his astonishment seems now that lesbian chic has completed its march into the mainstream. Standing in a supermarket queue last week I found myself eye-to-eye with a pair of naked blondes who were cupping each other's breasts on the cover of a lad's magazine.

It wasn't until I'd left the shop that I realised the strangest thing about the encounter: I had hardly even registered it.

Semi-pornographic displays of lesbianism - generally performed by straight girls for straight boys - have become so ubiquitous as to be almost unremarkable.

When Big Brother contestants Makosi and Orlaith had a "steamy lesbian romp" on national television, the tabloids dutifully recorded it - but no eyebrows were raised. Why would they be, when much steamier fare is so easily available?

This month's Front magazine, for instance, boasts a photo-story headlined "Rug Munchers: Terri and June enjoy a picnic in a field". Curiously, there is not a Thermos or a pork pie in sight.

For these lesbians, picnicking mostly involves spreading your legs and assuming a look of bored ecstasy while a girl with inflatable breasts pops a cherry into your mouth. There are no fewer than five Sapphic-themed photospreads in the September issue, including a regular slot called "Just Add Lezzas".

Should you wish to see hot lesbian action in the flesh, there's no longer any need to venture into the red-light district. At a recent motor show at Birmingham's NEC, girls in lacy G-strings were paid to writhe around on car bonnets touching tongues.

Nor is it just glamour models who pose as lesbians for the titillatation of heterosexuals. A study last year found that American high schools were experiencing a sudden explosion of Sapphic activity - but only in public.

Playgrounds and teenage parties were suddenly rigid with snogging girls who, when questioned by researchers, admitted that they were only doing it to pick up boys.

And if it has happened in America, you can be certain that it's happening here. Children learn from popular culture - and the lesson they seem to have absorbed is that lesbianism is a sex toy for straight people.

All this is, I suppose, an improvement on the bad old days of officially sanctioned homophobia. But I'm not sure that one could exactly call it progress. Queen Victoria famously refused to believe in lesbians - and, in its own way, so does modern popular culture.

The lesbians this culture serves up, with their cartoonish figures and expressionless eyes, are not the real thing.

They are not even pretending to be the real thing - because who would be turned on by a couple of women in stout shoes who love each other?

The south coast of England is bristling with retired WRAF officers living together in domestic bliss, but you never see them in magazines. They don't fit society's "Just Add Lezzas" slot. For that, you have to be faking it.

Jemima Lewis @ Guardian