Was deciding on a winner for the Booker prize, a friend asked at the awards ceremony, a bit like giving birth? She then relayed the story of how, after carefully nurturing her pregnancy for months, the doctors became increasingly desperate to get her baby out before something went wrong. And there was the happiest of endings, when her child was born safely, in good health.

Yes, I said, it was a lot like that. Only at that point, we discovered it was twins.

Much like the mysteries of conception, I can’t tell you why we judges were given the books we were given this year. Nor can I explain how the precise configuration of our life stories, professional experience, personalities and behavioural tendencies led us to a marathon meeting, with just barely hours to go until the ceremony itself, still arguing over how to choose a winner. On the details of those deliberations I am sworn to secrecy. But all of these factors mattered.

It was a shock to us all to discover how dramatic the final decision would be. But choosing a winner for the Booker is a curious thing. You read, read and read. Each month you meet your fellow judges and look back, in awe, at the distance covered. Until one day, you have to somehow condense all of this to a single book.

It’s an inevitably problematic task. Every single book on our longlist of 13 novels deserves to be read by everyone. I’m still mourning some of the books we had to eliminate at that stage. Never mind the shortlist of just six, each and every one good enough to win the prize.

How do you judge the titanic career, the contribution to culture of Margaret Atwood, against the sheer beauty of Elif Shafak’s Istanbul? How do you compare the haunting Igbo tragedy, told by Chigozie Obioma’s Odyssean narrator, to the Ulysses-like audacity of Lucy Ellmann? How do you pit the phenomenon of Salman Rushdie against the quality and consistency of Bernardine Evaristo, who was in my view hitherto hugely underrated?

You can’t compare them. But you can recognise them both

In the end, we refused to comply. We chose two winners. The outcome would always be imperfect, because it was an impossible task. I’m proud of our decision.

I’m bemused by the criticisms, many of which stem from the fact that the Booker rules stipulate that only one book can win. I witnessed journalists – a tribe of professional troublemakers of which I’m proud to call myself a member – outraged that we dared to break the rules. I’ve seen lawyers, whose profession involves interpretation and the application of principles of justice, complain that we did not adhere to the letter of the law. I’ve heard people complain that we didn’t give it to Atwood alone, or Evaristo alone. I’ve seen plenty of people question how you can ever compare the two.

You can’t compare them. But you can recognise them both. And I’m glad that this is what we did.