But while Glenda coyly admits to hitting the make-up box "occasionally", most women have a far more intimate and long-standing relationship with this most ancient of adornments. What separates the hard core users from make-up virgins like our Glenda is a state of mind. While she may dabble for short-term effect, the more habitual among us view a certain amount of make-up as an essential element of the daily armour; we'd no more cast it aside than go without underwear. At the heart of many women's reliance is the belief that one dab of a certain cosmetic, however small, is a crucial addition to the image that they present to the world. Without it they would feel vulnerable - naked in fact.
Paula Smyth, 35 and a researcher, has worn make-up since her late teens and happily admits that she is a chronic addict. "I can't leave home without foundation, mascara and, until recently, liquid eye-liner. Now, I can just about get out of the door in only foundation. I'd feel so undefined if I had to go without." Her reliance stems from an unshakeable belief that her appearance, especially her skin, is not so much improved with it on but totally unacceptable "au naturelle". "I look so rough and, I've been told, overtired," she says. "It doesn't make me feel better - it's more a case of bringing me back to zero." Like a long-term reliance on drink or drugs, a make-up habit doesn't perk the user up, it just makes them feel normal. "I see myself as a bit feeble because I am addicted to it," she admits. "I'd prefer not to be. But, basically, that's saying I want to look different. The reality is I look worse without make-up."
Although many women rely on a certain amount of make-up, they readily admit that the difference before and after is probably minimal. "I know no one would really notice the difference if I didn't wear mascara," says Suzi Mortimer, 26 and an assistant personnel officer. "But it makes me feel more comfortable." Shahla Rushworth, 27 and an advertising librarian, agrees. "I accept it's probably a psychological thing," she says. "It's the whole business of 'putting on my face'. Afterwards I feel healthier, more alive and polished."
Common to all the women I spoke to was a fixation on one particular product which they viewed as some sort of panacea; a liquid or powdered source of daily confidence. Angie Jackson, 27 and a designer, has a foundation fixation but also wears eye-liner and lipstick. "I couldn't be seen at work without foundation - I even wear it in the house when I'm on my own. Not wearing it would be like walking round naked," she says. "I feel quite challenged by girls who don't wear any - I feel a bit threatened, almost like, 'How come they're confident enough not to wear it?'"
Sarah Jackson, 23 and a PA for Channel 4, has been told by friends that she looks more attractive without make-up. But she's not convinced. "I couldn't do without my brown liquid eye-liner. I know I've got quite big eyes but they'd just disappear without a line underneath. When I take it off in the evenings, I always think, 'Oh my God'."
This is certainly reflected in recent make-up sales. According to Mintel's 1996 forecasts, sales of face make-up are valued at around pounds 204 million; lipstick and glosses pounds 138 million and eye make-up pounds 162 million. With the trend for a more natural image in the early Nineties interest in make- up dwindled, but since 1994 glam has taken off and sales are shifting again. In addition, the number of women in their mid-forties and over now using make-up has increased by 21 per cent.
Is this just a fashion fad or part of the general pressure to look good at any age? According to Sheila Rossan, lecturer in psychology at Brunel University, women wear make-up for the ritual itself as much as the end result. "Talk to most women and they'll say it's not because they want men to come onto them - it's not that overt," she explains. "It's fun to dress up. It makes us feel special. You do it for everyone, although you must do it for yourself first." Which seems to be the billion-dollar question. Who exactly is that small but subtle slick of mascara, dutifully applied every morning, really benefiting? Yourself, those around you or, as is more likely, a bit of both? Shahla says, "In a way it's for the opposite sex but it's also for my own self-esteem. You do want to be appreciated by others but it's for me first."
Martin Skinner, social psychologist at Warwick University, believes there is a more primitive drive at work. "It's about sexuality. Make-up accentuates certain features, like reddening the lips. Animal behaviourists talk about it as 'labial mimicry' and I wouldn't rule that out." He adds, "If you wear a certain amount of make-up, surely men are going to look at you differently?" For that reason, maybe, Germaine Greer was driven to write in The Female Eunuch: "I'm sick of peering at the world through false eyelashes, so everything I see is mixed with a shadow of bought hairs... maybe I'm sick of the masquerade."
But since she expressed those sentiments more than 25 years ago, many women feel that make-up is less a repressive ritual and more a form of individual expression. Skinner explains, "I think it's a way that people can exert quite an influence on how others respond to them. It's something you can control which, I guess, could make it quite addictive. It must be quite a buzz," he adds rather wistfully. Certainly, make-up offers a visual possibility that will forever remain a mystery to most men - shaving is about as varied as it gets for them.
As Paula says, "It is nice to get out of bed in the morning, look at yourself and think, 'Well, at least that's not it. There's a lot more I can do here.'" Perhaps Glenda feels the same way, too.