I FIRST met Harold Pinter in the early 1970s, when I sat on a sunlit lawn at Shepperton studios north of London interviewing him about Peter Hall's film of The Homecoming. That went well enough, and Harold even told me that the famous “Pinter pause” owed a lot to the American comedian Jack Benny, whom he had seen at the Palladium in the 1950s.

There was a distinct froideur after my review of his play Betrayal at the National Theatre in 1978. As I wince to recall, I wrote that Pinter “has betrayed his immense talent by serving up this kind of high-class soap opera”. A few months later the play won the top prize at the Society of London theatre awards. In his acceptance speech, Pinter unveiled his dentist's smile and said “I must be the most surprised person in the room, with the possible exception of ... [long pause] ... Michael Billington.” A thousand heads turned towards me as I slumped into my seat.

It took a while to get over that. I remember a ludicrous occasion when Pinter and I found ourselves standing in parallel entry queues one summer at JFK airport. As the lines gradually diminished, we ignored each other and maintained an immaculate, frosty silence. The thaw only set in when I interviewed him for a book I was writing on Peggy Ashcroft. He was not only helpful, he gave me a copy of his play, One for the Road, inscribing it “You didn't like it much but what the hell?”

The real breakthrough came in 1990 when I presented a four-hour programme on BBC radio celebrating his 60th birthday and charting not just his theatrical career but his passion for poetry, politics and cricket. In 1992, out of the blue, came an invitation from Robert McCrum, chief executive at Faber, suggesting I meet with him and Harold to discuss my writing a short book on Pinter's politics. At some point over lunch Pinter turned to me and said “Of course, you can talk to anyone you like about my life.” I realised, to my astonishment, that I was being given the green light to write a full-scale biography.

That led to four years of research and writing that taught me a lot about Harold Pinter. But what exactly did I learn? Most obviously, that his plays were almost invariably triggered by some memory or incident from his past. I also learned that Pinter's politics were the product of a rage against any form of injustice, partly the result of his postwar Hackney (east London) youth, in which he and his friends were appalled by the licence given to anti-Semitic organisations. If any later episode fuelled that anger, it was the American government's proven involvement in the 1973 overthrow of President Salvador Allende.

I realised that Pinter's politics were driven by a deep-seated moral disgust at the way western states not only manipulated language but often undermined the concepts of “freedom” and “democracy” to which they claimed exclusive entitlement.

But Harold's anger was balanced by a rare appetite for life and an exceptional generosity to those he trusted. I saw that in myriad ways, large and small. He couldn't have been more generous in giving me access to his life, his manuscripts, even his study at one point, we played Box and Cox as I worked there in the afternoons and he in the mornings.

Sometimes his help was purely practical. A few years back, when I was required to have an endoscopy, I asked Pinter's advice as to whether I should have an anaesthetic, since the hospital implied that real men didn't. “Don't be so ... silly,” said Harold, “of course you do with that tube stuck down your throat.”

Pinter was, even more than most of us, a man of contradictions his fierce concern for language was balanced by an equally warm regard for individuals. His friend Michael Colgan, who runs the Dublin Gate Theatre, tells a great story of recently going out for drinks with Pinter in a posh Dublin hotel. As they placed their drinks order with an over-enthusiastic waitress, she cooed at them, “No problem, no problem.” Pinter looked at her levelly and announced “I wasn't anticipating one.” A reminder that you don't waste words in Pinter's presence.

If that sounds harsh, I can only recount an amazing experience I had two months ago when I directed Pinter's Party Time, Celebration and a staged version of his Nobel lecture with drama students at Lamda, the London Academy of Music and Dramatic Art. Pinter had promised to come to the final performance and, on a cold autumn Saturday, he and his wife, Antonia, duly turned up. Not only that. As the cast gestured towards him at curtain-call, he struggled to his feet with great difficulty, shook them individually by the hand and made an impromptu speech expressing his admiration for their performance. It was something neither they, nor I, will ever forget.

Only later, when we had supper, did I realise just how desperately ill he was and what it had cost him, physically, to attend the performance. It was almost the last time I saw him and it reinforced something I had long known that Pinter wasn't simply the finest dramatist of his generation, he was a man with a great heart.

— The Guardian, London