Hay Festival has been a big success once more, with around 50,000 visitors swelling the Powys town's 1,300 populace.

It has been a marketplace for ideas, stories and writers in need of the odd plug for their new releases.

On Sunday, the festival was drawing to a close with a contribution from the Briton who helped crack the genetic code for human life.

Campaigners have backed Germaine Greer's stance

Dr John Sulston unlocked the key to a third of the human genome, together with an international public consortium - a major scientific breakthrough.

His Cambridge team criticised a private US gene firm's attempts to withhold from the public details of the human "book of life."

As literature enthusiasts prepared to leave Hay, Sir Sulston spoke about his own publication, The Common Thread, co-authored with Georgina Ferry.

Rival schools

The book was last week nominated for the BBC Four Samuel Johnson Prize - non-fiction writing's most profitable award with a £30,000 winner's prize.

A festival spokesman said in a programme: "He is frank about the negotiations with Clinton and Blair...

"... and the competition with Craig Venter and Celera Genomics that threatened to undermine the attempts by the international community to make the sequence available for all humanity."

His talk underpins an earlier lecture from cultural theorist Francis Fukuyama, who warns of the implications of the biotechnology revolution in his book Our Posthuman Future.

And there was another talk on the impact on society of genetic cloning.

We feel strongly about the way Nestlé is marketing abroad - I hope it will make people stand up and look at large companies

Derek Addyman, bookshop owner

In keeping with the rest of the week, however, the final day was also taking a less scientific bent.

Italian chef Antonio Carlucci is giving culinary tips in the final talk of a series dedicated to food.

Pioneering eisteddfod poet Mererid Hopwood introduced visitors to the unique Welsh-language Cynghanedd verse and writers shortlisted for the Orange Prize for Fiction read extracts from their work.

The week's other highlights have included gigs from Senegalese singer Baaba Maal and an inspiring talk from African-American author and activist Maya Angelou.

Nestlé issue

But "the Woodstock of the mind" did not pass without controversy.

Prior to the 13 May launch, feminist author Germaine Greer and Booker Prize nominee Jim Crace pulled out in protest at Hay's sponsorship by Nestlé, in whose venue chef Carluccio was speaking Sunday.

The pair oppose the food giant's marketing of powdered baby milk in the developing world.

With the book event closing, campaigners said over 500 festival-goers had signed a petition backing the cause.

Bookshop owner Derek Addyman told BBC News Online: "We feel strongly about the way Nestlé is marketing abroad.

"I hope it will make people stand up and look at large companies and what effect they have in the Third World."