Can you hear me at the back?

Public lectures are undergoing a renaissance, with soaring attendances for even the most arcane subjects. Jonathan Brown meets the new intellectuals

January's traditional drive for self-improvement typically focuses on righting the physical wrongs of the season's overindulgence. But this year, a surprising number of those in search of a new diet to help them to start the new year on the right footing will be looking not to the body but to the mind as their arena of battle.

They will be part of a growing trend. For not since the days when Victorian working men queued in the rain to listen to John Ruskin holding forth on the relationship between beauty and truth has the murmur of popular intellectual discourse grown so loud. And this new spirit of intellectualism is restricted not just to cocking an ear to Melvyn Bragg chairing debates on the great issues of the day on Radio 4, or Alain de Botton contemplating the metaphysics of the package holiday on television. It is something in which people are actively taking part.

The evidence was clear at a weekday lunchtime recently when 150 people settled down to learn a little more about the extraordinary life of the Pre-Raphaelite muse-turned-artist Lizzie Siddal. Because of the numbers that turned up, Joanna Banham, who runs the public-lecture programme at Tate Britain, had been forced into a last-minute change of venue, opening up the 200-seater auditorium to accommodate them.

A lecture last month on the Portuguese artist Paula Rego was packed to capacity, and disappointed art lovers were turned away. The lunchtime lectures are free to the public and have a loyal and growing following. But as the booming trend for book clubs, literary festivals and discussion groups has evidenced, it is not just at the major galleries and learned societies that this spirit of self-improvement is flourishing.

Any week, in London alone, there are a bewildering array of lectures on any number of subjects to choose from. Attendance is up by as much as 60 per cent at some institutions, with thousands of people taking in a formal lecture each week. In the busy run-up to Christmas, for example, the portrayal of flunkeys and scullions in Georgian times was being discussed at the National Portrait Gallery; the Institute of Classical Studies was debating the culture of prediction in ancient society; and their colleagues at the Institute of Archaeology were considering the evolution of bow-and-arrow technology in Mesolithic Scandinavia. The question at Euston House, meanwhile, was whether madness is female and what role women played in the evolution of German psychiatry in the 1930s.

Lectures and public talks achieved massive popularity during the Victorian age, so it is appropriate that at Tate Britain, Lizzie Siddal's story was recounted by the author Lucinda Hawksley, the great-great-great-granddaughter of Charles Dickens. Dickens himself commanded vast audiences in the 19th century. His speaking tour of America created the first known ticket touts or "speculators". Oscar Wilde believed himself an even bigger attraction than Dickens, while Ruskin, artist, writer and philosopher, was celebrated for taking his lectures to Britain's industrial cities of the North.

But it was not all snowy-haired academics and doughty bluestockings in the Tate Britain audience. The video artist Michael Curran, 41, is a regular lecture-goer. "The intellectual level of television has deteriorated dreadfully. I have one but I'm getting rid of it," he says of his reasons for attending. His companion, the cowboy-hatted singer-songwriter Heather Jones, agrees: "Television is now just bedtime anaesthesia."

Joanna Banham believes that the growth of what she calls "the learning society" is behind the popularity of her lecture programmes at Tate Britain. People also enjoy the element of "live performance" that they offer, and the fact that they can go with a friend and, much as they would after a film or play, discuss what they have heard afterwards. "There's a real thirst for information, and it's a pleasure to hear someone speaking eloquently while looking at beautiful images," she says.

At the London School of Economics, they've been enjoying a blockbuster season of big-name speakers playing to packed houses. Following the success of a series of lectures by former Foreign Secretaries last year, Lords Lawson, Lamont, Healey, Howe and Kenneth Clarke have been reflecting on life at 11 Downing Street. Since 2000, more than 17 current or past prime ministers or presidents have spoken at the LSE. Since October 2004, 13,100 people have attended public lectures there, nearly 60 per cent more than in 2003. The average audience is 319 people.

Free Thursday-lunchtime music events are also growing in popularity, pulling in more than 1,500 people so far this term. According to the LSE director Howard Davies, the success is down partly to location and partly to reputation. "We're lucky to be able to pull in so many heavy-hitters - almost every lecture is full," he says. Research by the university has revealed that six out of 10 who attend are aged between 20 and 30. More than half are women. Only seven per cent are of undergraduate age, while a further two per cent are aged over 70.

One such is Ben Haines, 79, who must rate as one of London's most inveterate lecture-attenders. After a career trotting the globe on behalf of the British Council, he retired back to London and was looking for something worthwhile to occupy his time. "I wanted to get back in touch with what people were talking seriously about in London," he says. He now attends several lectures a week, often on subjects relating to Islamic culture and history. He also compiles what must be the fullest list of free lectures and talks in London, published on the Victoria Research Web (www.victorianresearch.org/lectures.html).

At the School of Slavonic and East European Studies in London, Lauren Holmes, 25, is getting to grips with the equivalent of the Arts and Crafts movement in Russia. She likes the lecture format as it allows her to pick and choose what interests her. "It's not like an adult-education course, where you have to sign up for a several weeks. There isn't the same commitment."

The School of Oriental and African Studies has also witnessed a surge of interest, particularly in complex areas of debate such as Israel's Palestinian problem, and, more recently, the war in Iraq. According to Professor Tony Allan, who lectures on the Middle East, young people in particular are drawn to controversial topics, especially those that dominate the news. "We could fill a lecture room every day if we discuss the crisis in Iraq, Palestine or the Middle East in general," he says. Other specialist topics are also generating a loyal following. One reason, he believes, is the power of the internet. People interested in certain subjects link up to form online intellectual communities and are thus able to publicise events and new research among themselves.

Meanwhile, at Tate Britain, Lucinda Hawksley signs copies of her new book, Lizzie Siddal: The Tragedy of a Pre-Raphaelite Supermodel, and fields questions. "People like to learn," she says later. "They may get fed up with it at school or university, but once they are working they start to miss it. Up to now, Lizzie Siddal has always been the preserve of academics. I want to help ordinary people get their hands on her."

Ordinary people, it would seem, want to get their heads round her, too.

Five of the best

Saturday 8 January

A Tooth for a tooth: dentistry through the ages. Thackray Museum, Leeds (0113 244 4343), 10am

Tuesday 11 January

Man and alien species: the red-bellied beautiful squirrel in Argentina. Dorset County Museum, Dorchester (01305 262735), 6.30pm

The UN at 60: the hidden story of success. Royal Museum, Edinburgh (0131-247 4219), 6.30pm

Wednesday 12 January

Households and houses in late 17th-century London. Institute of Historical Research, Senate House, London (020-7862 8740), 5.30pm

Thursday 13 January

Aggression: the biology of war and peace. Gresham College, Barnard's Inn Hall, London (020-7831 0575), 1pm