When they first got hooked on the habit, it gave the little group of women neighbours in Goole, Yorkshire, "a delicious feeling of decadence", about which some of them still feel guilty.

They pooled their tea rations, prepared food to keep them going, went into the poshest room in the house and got down to it.

They sat down to listen to somebody reading two chapters a day from a library book, then talked about it.

That was in 1948. The book was Kathleen Winsor's searing bodice-ripper Forever Amber, about a mistress of King Charles II. They were one of the first modern reading groups, the forerunners of a movement which has swept Britain since the 1990s and is still growing.

Now, with an estimated 50,000 people in these groups, taste has moved up several notches into literary fiction. The runaway favourite is Captain Corelli's Mandolin, by Louis de Bernières, followed by Angela's Ashes, by Frank McCourt. Other popular titles included Sebastian Faulks's Birdsong, Beryl Bainbridge's Every Man for Himself, E. Annie Proulx's The Shipping News and Pat Barker's Regeneration.

Readers still meet mainly in people's homes but also in prisons, north Norfolk beach huts, pubs, a zoo and a dentist's waiting room.

One group is tackling Dickens's Little Dorrit in instalments, to recreate the excitement of Victorian readers, for whom the book was serialised. And a group in Britain with time to spare is inching through James Joyce's Ulysses.

These trends are disclosed today - World Book Day - in Jenny Hartley's new book Reading Groups*, the first research into the communal habit.

Ms Hartley, principal lecturer in English literature at Surrey University, studied more than 1,000 readers in a total of 350 reading groups. Their excited and engaged voices, she writes, "sound as if they're living on a different planet from the current batch of literary and social commentators weighed down by millennial lamentations".

The lamentations are about a book culture allegedly drowned out by media culture, the internet and other pressures on leisure.

Ms Hartley said her results show that "reading groups read widely and well and the literary fiction they favour is in good heart and financial shape both in the US and the UK".

Historically, too, groups have had more social influence than commentators allow, she adds. In late 19th century America, women's reading groups provided the sinews of the women's suffrage movement. In Britain, 69% of groups are all-female, with 27% mixed and only 4% all-male. But people under the age of 30 now joining their first groups prefer mixed company.

Two thirds of members are more than 40 years old, with 20% in their 30s and virtually nobody younger than this.

The groups are almost all newish, with 67% less than five years old and 79% less than a decade old. More than half the members in nearly all groups have been in higher education and two thirds are in paid work. Geographically, they are evenly spread, with slightly more in the countryside.

"We share a common culture, which we take for granted, but which comes under scrutiny every month," one reader told the survey.

Another said: "I love the buzz and the sharing of opinions and chat." In others, the old motive which stirred their parents and grandparents in Goole still lives: "We love 'having to read', so don't feel guilty. It allows me a few legitimate hours to myself away from the kids".

*Oxford University Press, £5.99 paperback

Reading groups' favourites

1 Captain Corelli's Mandolin, Louis de Bernières

2 Angela's Ashes, Frank McCourt

3 The God of Small Things, Arundhati Roy

4 Enduring Love, Ian McEwan

5 Cold Mountain, Charles Frazier

6 Fugitive Pieces, Anne Michaels

7 Alias Grace, Margaret Atwood

8 Behind the Scenes at the Museum, Kate Atkinson

9 Memoirs of a Gheisha, Arthur Golden

10 Birdsong, Sebastian Faulks

11 Every man for himself, Beryl Bainbridge

12 Snow falling on Cedars, David Guterson

13 Larry's Party, Carol Shields

14 The Reader, Bernard Schlink

15 = Beloved, Toni Morrison; The Shipping News, E Annie Proulx

17 Ladder of Years,

Anne Tyler

18 = Regeneration, Pat Barker; A Patchwork Planet, Anne Tyler

20 Quar-antine, Jim Crace

21 A Thousand Acres, Jane Smiley