Maeve Binchy, whose latest novel, Evening Class, is published tomorrow, says every evening class is founded on an "insane" dream.
"It's an act of faith in the future based on no reality at all," she said. "You see yourself as a different person by the end of the course. That's what hooks you ... We've all been to school. We all think that since school starts in September it's a time for new resolutions.
"I'm very dreamy about these things myself. I think I'm going to be really successful. I see myself as Flower Arranger of the Year. I think I will be fluent in a language - speaking like a native - even though we're chanting phrases and doing exercise three on page 23.
"I did calligraphy once. It wasn't just that I thought I could write nice lines - I could see myself illuminating manuscripts."
Latest figures show that more women go to classes than men, and studying is most popular in the South-east and least popular in parts of the North. While evening classes were launched at the beginning of the century by university extra-mural departments and the Workers' Educational Association as a "highway" of opportunity for millions of children excluded from higher education, today's students do not always share such lofty ideals.
True, there are adult students using "access" courses as a first step to a degree, and people wanting to engineer a career change. But they are also used by people wanting to take up fads and fashions, and seek out sex. It is not so much the content of the course but the content of the class that counts.
Bridget Connolly, 30, taught Spanish to Essex taxi drivers who owned timeshares on the Costa del Sol. A letter from a pupil who dropped out after three lessons made her question precisely what service she was providing.
"He said he was sorry he'd stopped coming and that I shouldn't take it personally," she remembers. "He said he didn't think it was much use because Eva - who was blonde and Czech - was obviously married, but if I felt like it I could let her know she was very tasty."
This autumn more than 35,000 options are available in Greater London alone, from "Manual lymphatic drainage" and "Fly tying for trout" to "How to get what you want and still be liked" and "Fat-burning and sculpting" (although even these pale before the Californians' "Earthquake preparedness seminars").
Few publications can give a quicker insight into the obsessions of the age than an adult-education handbook. "Alterna- tive Health is vast now," said Philippa Miller, editor of the capital's course guide, Floodlight. "Reflexology and Shiatsu Massage both have their own headings. A couple of years ago we hardly had any courses on the Internet. Now we have a whole section on it and Computer Studies spreads over page after page after page."
Said Ms Binchy: "In England, all my friends say their 18-year-olds are all going to Irish dancing classes. It used to be seen as terribly unsexy, but after Riverdance and Lord of the Dance, everyone's discovering that it can be sexy." Teachers are not ashamed to cash in: there are even two courses called Riverdance available in London.
Other courses are perennially popular. Art and music classes top the league, while modern languages combine an irresistable mixture of practical skill, nostalgia for a foreign place and the promise of a glamorous liaison.
John Richards, 40, started Russian evening classes for strictly educational reasons. He kept going back for more. "There was a certain glamour about doing Russian, particularly in those days. I suppose, if I'm being honest, I recalled something my history master said at school - 'Remember, boys, the most glamorous girls always do modern languages' - and I think he was right."
Evening classes, for him, were "a predatory thing" - "I was a single man in London, alone, looking for attractive women who also have intellectual interests. The social life and possibility of romantic excitement played a strong part in keeping me going there for nine years of evening classes."
Intensive course weekends were an occasion for "getting it together". On one such weekend, he met a certain Julia, who was "just stunning". The affair went from there.
"There was one married woman and I think an affair wouldn't have been out of the question. She certainly confessed she had thoughts she shouldn't have and I think she was up for it. It all sounds very uncivilised but it wasn't."
Unlike most real-life evening classes, all the students in Ms Binchy's account of an Italian class at Mountainview School in Dublin stick out the course. Ms Binchy herself is no stayer. She has only ever made it past lesson three once. "I went to lesson four in Italian. That's what made me an absolute authority and write a book on it."
Catherine Peters, a retired professor at Somerville College, Oxford, teaches evening classes in literature in Oxford. After an initial fall- out, Ms Peters's pupils tend to stay the course. "What happens is usually we get a great crowd at the first meeting. Those who don't think it's going to live up to their expectations drift away, but there is a hard core which stays and completes the two terms, which is 20 evenings. Not only that, they come back year after year." She added: "There are a lot of retired people who say it is the only thing that keeps them going. They say it ought to be on the National Health."
In 1994, the most recent year for which figures are available, 4 per cent of the female population in England enrolled on adult-education courses, as did 1.6 per cent of the males. The participation rate in evening classes is generally higher for women than men and is highest in the South- east. The lowest rate for both men and women is in Yorkshire and Humberside.
While evening classes might be about dreams, they provide their students with little escape from reality. They are as much prone to the political machinations of town halls and Whitehall as any other area of education.
Take students numbers. These, said Ms Miller of Floodlight, would be much higher but for the recent increases in fees caused by cuts in local- authority spending. She said: "It may cost pounds 60, it may cost pounds 100 a term. Only five or six years ago the fees were well under half that."
Classes can also fall victim to ideology. "I used to take a local-authority ballet class," said one student. "When Labour won control of the council they cancelled it and replaced it with wheelchair dancing."
London's top 20
1 Practical art (639 courses ) - plus calligraphy (51)
2 Music (669) - including 95 for guitar
3 French (476)
4 Dance (416)
5 Spanish (364)
6 Access to higher education (337)
7 German (335)
8 Cookery (316)
9 Physical education (302)
10 Accounting (291)
11 Italian (279)
12 Business Studies (274)
13 Learning difficulties (classes for people who have) (264)
14 English as a foreign language (256)
15 Mathematics (248)
16 Word processing (240)
17 Information technology (235)
18 Psychology (228)
19 Children and childcare (227)
20 Photography (215)