How did they get in? Hay Festival's success spawns its own fringe

Each May Peter Florence pitches his marquees in a field below the town of Hay-on-Wye on the Welsh-English border, ready to receive 100,000 visitors to his Hay Festival.

They are drawn by star names – Nigella Lawson, Chris Evans and VS Naipaul have already spoken, and Julian Assange is due onstage later today – as well as camaraderie and a love of books.

However, this year, the festival has been punctuated by references to "the other place". A rival festival has not only pitched up on Florence's territory but it is also seducing some of his high-profile speakers, for whom he has provided accommodation and travel.

How the Light Gets In is a philosophy and music festival, started up three years ago by Hilary Lawson, in the grounds of an old chapel in Hay, surrounded by a village of yurts and canvas canopies. Its name comes from a Leonard Cohen lyric.

This year the journalist Polly Toynbee, philosophers AC Grayling and Mary Warnock and the poet Simon Armitage are among the high-profile speakers drawn to both festivals.

Lawson's hippyish theme and younger crowd also seduced Martin Amis. Last year, after speaking at Hay, he invited himself to speak at How the Light Gets In. "It was a mistake," says Lawson. "He didn't have anything interesting to say. We aren't here to help people sell their books, it's about ideas."

This year How the Light Gets In has pulled off a coup, and cannot be accused of borrowing Florence's talent. Tomorrow the Business Secretary, Vince Cable, will be speaking at two events there on global futures. Over at the Hay Festival, the top political guest is the less exciting Yvette Cooper, the shadow Home Secretary.

Lawson has been accused of "eating off Peter's plate". Last year a rumour went round that Florence had told one of his writers who dared to perform at "the other place" that they would not be welcome at Hay again.

"You are always going to have smaller fringe events that spring up," says a spokesman for Florence. "But, as long as everyone's clear about their own identities and looks after their guests, then it's going to be fun."

Florence's empire is hardly struggling. Since it started 33 years ago, funded with the winnings of a poker game, it has spawned sister festivals around the world.

It still attracts the great and the good of the London publishing world who rate Hay so highly that books are engineered to appear in May in the hope of a gig there.

Lawson has so far resisted the corporate route, although there's a sense that a big investment isn't far away.

"I was invited, with several other arts organisers, to a lunch with the director general of the BBC [Mark Thompson] and other executives a month ago. They were looking for new ways of covering the arts," says Lawson. Florence was also there. One can't imagine he stomached the meal too well.

So, which is better: Ha y , or How The Light Gets In?

Science

Brian Cox has star power as TV's favourite science presenter but for pure science wattage the D:Ream keyboard player turned physicist, who is speaking at Hay, will struggle to outshineRolf-Dieter Heuer, the man in charge of the Large Hadron Collider.

Winner: HTLGI

Children's Literature

It would be cruel to ask their readers to choose between equally beloved Philip Pullman, who is reading at How the Light Gets In, and Jacqueline Wilson, but when it comes to popularity – and pound signs – Wilson edges it with 30 million book sales in Britain alone.

Winner: Hay

Politics

One of How the Light Gets In's biggest coups has been signing up the Business Secretary, Vince Cable, who be talking today about "global futures" (bleak, one expects). Over at Hay, visitors will have to make do with shadow Home Secretary, Yvette Cooper.

Winner: HTLGI

Art

They've all won the Turner Prize but Martin Creed, who is speaking at How The Light Gets In, says he "wouldn't call himself an artist" and has had eggs chucked at his Turner installation, so top billing should go to eccentric duo Gilbert & George.

Winner: Hay