Then join the queue. There are never enough ladies' loos - and Ruth Picardie, for one, is tired of crossing her legs
The baby-sitter has finally arrived, smelling only slightly of Martini. Miraculously, you have found another pair of unladdered tights after a run-in with a wicker chair. Your new tinted contact lenses (sky blue) look, well, unusual with your colouring. And, after a mere 20-minute search, the car keys have turned up in the back of the cutlery drawer. Purse. Lipstick. Nurofen. Yes! Your big night out is finally happening. You are going to the opera.

It is only when you get to the end of the street that you remember. Idiot! Moron! How could you forget? You stop the car, beat your head against the dashboard, decide against going home. Now you will have to miss the end of Act One or suffer for the duration of Act Two. Another evening turns into a pumpkin.

Male readers may well be mystified by now. What could our harassed everywoman have forgotten? The racing results? Her emergency condoms? An adequate supply of Maltesers? Female readers, on the other hand, are only too familiar with the sorry story and sorrier moral. Always go before you leave.

As anyone who has ever queued for a ladies' loo will know, Britain's public buildings almost invariably have fewer toilets for women than for men. And even those with equal provision are part of the problem: according to a survey carried out by Cornell University in the US, men spend an average of 45 seconds using public toilets while women take 80 seconds. "Actually," says Peter Viggers, the Tory MP who has been campaigning for better provision since seeing a queue for the loo at the Coliseum, home of the English National Opera, "you need three times as much space for women as you do for men."

It is not just Victorian theatres that are at fault, though they are notorious: London's Phoenix theatre, capacity 1,000, has a grand total of nine ladies' cubicles. A few years ago, women queuing for the loo during the interval went on strike, refusing to go back to their seats until the manager let them use the gents'. Sadly, the stand-in had no long-term impact: queues for the current show, Blood Brothers, are particularly bad. "Musical audiences tend to go more often," the manager, David Lyness, says somewhat mysteriously.

Modern buildings do no better: London Arena (capacity 11,000, urinals l94, ladies cubicles 73) is notorious. Meanwhile, queues at the capital's hangar-like night-club, Ministry of Sound - voted worst club toilets for four consecutive years by one clubbing magazine - can last for half an hour. Shamed, the management recently rebuilt the ladies' toilets as part of a pounds 500,000 club refit. There are now full-length mirrors, free cosmetics, an attendant, an expanded vanity area and 16 instead of eight cubicles. And the queues? "Still a mile long," says Bea, 24, who went to the grand opening.

What about shops? Surely if any public building is going to be properly provided with loos it is the department store, lunchtime haunt of the millions of Women Who Love To Browse. Think again, ladies. "I was in Selfridges' basement," recalls 31-year-old Jenny. "It was August, supposedly a quiet month, and the queue for the loo went down a corridor and back into the shop." Eventually she begged to use the staff facilities and, eight months pregnant at the time, a disaster was averted. Beware elsewhere in the store, too: the hair and beauty salon that inhabits the fifth floor boasts, bizarrely, five urinals and four cubicles for men and no facilities for women. Same story on the second floor: ladies' fashions is served by three urinals and two men's cubicles - great for transvestites but no one else.

It is not just the queues that have made ladies' loos a no-go area. The main subsidiary gripe is cubicle sizes. "At the Young Vic," reports a female theatre-goer, "there are four booths in a space designed for two. You have to be totally acrobatic to get in." Even if you do manage to avoid sitting on the sanitary towel disposal unit to close the door, there is nowhere to put your coat and bag. And if you are pregnant? Carrying shopping? Accompanying a child? Please, just stay at home.

Then there is the question of hygiene, not an issue that seems to bother men, judging by the notorious urinal smell that strikes fear and loathing into the hearts of female passers-by. Why do cisterns in public toilets take so long to refill? Why do water-saving taps only spray for three- and-a-half seconds? And why does the queue always impede access to the basins? Says Jenny: "It's the silent glare you get when you don't wash your hands that I can't stand."

Who is to blame for the great ladies' loo crisis? Theatre managers stigmatise the Victorians: "The Victorians obviously thought women didn't go out or didn't go to the loo," says the press officer for the Royal Court, whose pounds 16m lottery allocation is going partly on improving the ladies' loos, which presently number five, compared to nine urinals and three male cubicles. "In Victorian times," says the theatre's project manager, Tony Hudon, "ladies did not drink." Shame on you! For, as every GCSE history student knows, the Victorians were great hygiene pioneers. Who else but the Ladies' Sanitary Association (formerly the Ladies' Association for the Diffusion of Sanitary Knowledge), publisher of such marvellous titles as Wasps have Stings and Beware of Tight Lacing, successfully lobbied for the provision of permanent public toilets for women?

Other commentators blame women themselves, for taking too long and for indulging in the ancient female ritual of going en masse. "What do women do in the toilet?" wonders Jenny, rhetorically. "What are they up to? Eating a sandwich? Taking drugs? They're certainly not having a crap, that's for sure. No woman would have a crap in a public place." Mystifying, too, is women's fear of the automatic public convenience, or APC. A report on women's public conveniences published in 1990 by the Women's Design Service found that "APCs are feared and mistrusted by women users. The main worries are that the automatic cleaning process might start while they are using it or that the doors will fly open." Bizarre!

But enough of blaming the victim, just because women do not possess what Claire Rayner has called "that handy little gadget" which makes peeing so easy for men. And then there are periods, pregnancy, cystitis, lipstick that will not stay on past Act One. Whoever said it was easy being a woman?

The real baddie is, as even Peter Viggers acknowledges, the state. Local authorities are no longer obliged to provide public conveniences, as the management of Harrods knows only too well. "We are the public toilet facilities for the Knightsbridge area of London," says a spokesperson for the store. Hence the introduction, in June 1994, of the "superloos", all complimentary perfume and marble flooring, for which customers (except account holders, disabled people and mothers) pay pounds 1. And the queues? "I'm afraid it can still be a problem."

Government building regulations do not take into account women's greater need. BS 6465, which applies only to businesses in which food and drink are consumed on the premises, specifies that cinemas, for example, should provide three urinals and 12 cubicles per 250 men and only five cubicles for women.

What is to be done? Peter Viggers MP has retired from the fray. "I found myself being greeted with giggles as the ladies' loo man," he says, somewhat ruefully. Direct action can be hazardous: in l990, a feisty Texas gal, fed up queuing for the loo during a country and western concert in Houston, nipped into the men's. "There," she said as she left, relieved, "I left the lid up, just like y'all like it." Regrettably, an off-duty police officer heard her boast and she ended up in court.

While women shy away from the ultimate threat - pissing in public, like men - the situation looks bleak. And gents, now you know why ladies always cross their legs.