Twenty six years ago, the panel of judges were so unsure who should win the Man Booker in 1992 that they ended up with a tie: Michael Ondaatje and Barry Unsworth. But on Sunday evening Ondaatje edged ahead, with his bestselling novel The English Patient being named the best winner of the Booker prize of the last 50 years, in a public vote.

The Golden Booker was held this year to mark a half-century of the prize. A panel of judges read all 52 former winners of the award, with each assigned a decade from the Booker’s history. The Observer’s Robert McCrum, taking on the 1970s, chose VS Naipaul’s In a Free State; poet Lemn Sissay, reading the titles from the 1980s, went for Penelope Lively’s Moon Tiger; The English Patient was novelist Kamila Shamsie’s selection from the 1990s; Hilary Mantel’s Wolf Hall was nominated as the best of the 2000s by broadcaster Simon Mayo, and George Saunders’ Lincoln in the Bardo topped poet Hollie McNish’s reading of the 2010s Booker winners. The five books were then put to a public vote.

Speaking at the close of the Man Booker 50 festival in the Southbank Centre, London, on Sunday, Ondaatje said he had not reread The English Patient, which moves between a nurse tending a horribly burned man in an Italian villa at the end of the second world war and a tragic love affair from his past, since 1992.

“Not for a second do I believe this is the best book on the list, especially when it is placed beside a work by VS Naipaul, one of the masters of our time, or a major work like Wolf Hall,” he said, adding: “I suspect and know more than anyone that perhaps The English Patient is still cloudy, with errors in pacing.”

Ondaatje said he felt it was important to acknowledge the authors who never won the Booker prize, specifically naming William Trevor, Barbara Pym and Alice Munro.

Shamsie said Ondaatje’s historical novel received the most votes, with nearly 9,000 votes cast by the public. Previous “Best of Bookers” surveys – carried out for the award’s 25th and 40th anniversaries – were both won by Salman Rushdie’s Midnight’s Children.

Shamsie described The English Patient as the sort of book that “gets under your skin and insists you return to it time and again, always yielding a new surprise or delight”.

“Few novels really deserve the praise: transformative. This one does,” said Shamsie. “It moves seamlessly between the epic and the intimate – one moment you’re in looking at the vast sweep of the desert, and the next moment watching a nurse place a piece of plum in a patient’s mouth ... It’s intricately and rewardingly structured, beautifully written, with great humanity written into every page.”

Adapted into a multiple Oscar-winning film starring Ralph Fiennes as the desert explorer Làszlò Almàsy, Juliette Binoche as his nurse Hana and Kristin Scott Thomas as the married Katharine Clifton, The English Patient was one of the best-known books on the shortlist. Back in 1992, however, the two-hour meeting between Booker judges was “pretty bloody”, according to reports at the time.

“Every book on our shortlist had one passionate supporter and one furious antagonist. When at the final meeting we locked horns over the frontrunners, it was suggested that we should reach our decision by taking into account second choices – proportional representation,” the chair of judges, Victoria Glendinning, wrote of the meeting, admitting that at one point she had called a fellow judge a “condescending bastard”.

Reading the Booker winners of the 1990s, Shamsie said she had been struck by the fact that there were six years in which just one or no women were on the award’s shortlists. “God, can you imagine now if five years in a row the most women on a shortlist was one? ... That has changed in the culture,” she said.

But she said that The English Patient stood out, due to the Sri Lankan-born Canadian author’s treatment of his female characters.

“A lot of books by male writers are only interested in the lives of men – they may be wonderful books, but the women figure quite peripherally,” she said. “Hana to me is the centre of the novel, and is done with such love, care and understanding and complexity.”

Shamsie batted away suggestions that the novel had won because it was the best-known on the shortlist, thanks to the film adaptation. “Hilary Mantel is very well known too, and if you’re going to vote in something like this, you’re probably voting because it matters to you,” she said.

And The English Patient film, she said, focuses on Almasy’s affair, while for her, the central love story is between Hana and Kip, an Indian Sikh bomb disposal expert. “A lot of people when they’re reading the book are probably imagining Ralph Fiennes though, and that doesn’t hurt anything,” she said.