On a rare day of high-wattage sunshine that momentarily denuded the stygian gloom that is London in late winter, I spent an interesting hour at my U.K. publishers—Random House—listening to the sales and marketing team strategizing for the imminent publication of my 11th novel, Five Days (published in the U.S. by Atria). After the meeting, I headed out to lunch with my English editor, Susan Sandon, and my agent, Antony Harwood (known as Ant). As we walked toward a restaurant deep within the rabbit warren of streets in the borough of Westminster, a thought struck me—one that I articulated immediately to Ant: “It was 20 years ago today.”

Ant’s reply: “Sergeant Pepper taught the band to play.”

“Touché,” I said. “But something else happened 20 years ago today.”

On this same day in March 1993, I walked into Ant’s then-office on Regent Street with the manuscript of my first novel in the satchel bag slung over my shoulder (when manuscripts were actually hefty piles of paper). Having published three narrative travel books and having heard from my then-agent that he himself was trying to get his own first novel published, I’d decided to look elsewhere for representation. I knew I couldn’t continue being represented by a fellow budding novelist (the ups and downs of a literary career struck me as tricky enough already). Having auditioned one of London’s grande dame agents (it was like having an audience with Elizabeth I) and a new up-and-coming agent (whom I felt had no depth in the outfield—the American in me reaching for a baseball metaphor), I had been pushed in the direction of Antony Harwood by a London writer friend who was encyclopedically versed in all aspects of “the business.”

“He’s the guy for you—and when you meet him you’ll see why,” he said.

My friend was right on the money. From the moment I sat down in the chair opposite Ant’s desk, there was a flow of conversation and wit that underscored a shared passion for the written word. We were both in our 30s, both fathers, both Jewish (my Irish-American father from Prospect Heights, Brooklyn, having married the daughter of a diamond-district salesman from Yorkville in Manhattan), and both possessing a quirky yet pragmatic take on the realpolitik of life. And I could tell immediately he so got the complexities of trying to be a writer.

Choosing an agent is a decision weighty with import. Besides selling your books to your publishers, he or she is also going to be the one who will share with you all the profound highs and lows of a life in the literary trenches. As such, you better be certain that you are sympatico with this person, that you share a reasonably copacetic world view, that he can be your best ally.

What impresses me about Ant is that he can be as close or as professionally distanced an agent as you want. If you need a father confessor he is there for you (as he certainly was for me during my divorce). If you need a tough guy—as I did when a French publisher (not my own) took a novella of mine from an anthology and printed it, without permission, as a separate edition—he can play the bad cop with effective aplomb. If you need someone to ensure that your publishers are pressing all the essential sales and marketing buttons, he is the supreme diplomat. If you feel—as all writers do every 30 minutes or so—hard-done by the world, he is there to console you and tell you to snap the hell out of the self-pitying jag. And if you need a first reader, he is always scrupulously engaged and fantastically celebratory, or politic but direct if he feels there are problems.

In two decades together—through so many complexities and successes and setbacks and disappointments and wondrous surprises (in short, the usual stuff of life)—we have never had a dispute, a disagreement about money, or even a difficult conversation between us. Most tellingly he has always respected what I have always been about as a writer, and has never once attempted to influence my creative trajectory. Nor has he ever uttered that most limiting and destructive of words: don’t.

In a world where allegiances frequently shift, where marriages collapse, and friendships fray, Antony Harwood remains a constant.

“How do you put up with us all?” I recently asked him.

He laughed and said, “I truly happen to love writers.”

Antony Harwood sold Douglas Kennedy’s first novel—The Dead Heart—10 days after their first meeting in March 1993. Since then Kennedy has published 10 more novels, including bestsellers The Big Picture, The Moment, and Five Days.