"I do loathe explanations" is the Barrie maxim that should caution me in writing this new introduction to a book I thought I'd disposed of a quarter of a century ago. Another is "Beware, or you may get what you want" – a warning I found in one of Barrie's notebooks but always forgot to include in subsequent editions.

I didn't catch up with Peter Pan till my late 20s. As a struggling hack, I'd accepted the job of co-adapting the story for an American musical starring Mia Farrow as Peter and Danny Kaye as Hook. I knew nothing of Peter – I'd never even seen the Disney cartoon – but my mother knew a thing or two about him, having sung the somewhat sugary 'Peter Pan Song' at the beginning of every performance of the silent movie in her father's cinema back in the 1924. She lent me her copy of the play, urging me to also read the lengthy 'Dedication to the Five', in which Barrie breaks his own maxim by partially explaining how Peter came into being, referring to the Llewelyn Davies boys with enigmatic numbers:

Mia as Peter, captured with my Pentax.

Although this cry from the heart touched deep chords, had I not fallen in love with Mia Farrow things might have ended there. But I was keen to remain in her orbit, and justified my presence on the set by becoming the resident Barrie expert. My inherent inertia was further provoked by my friend Richard Loncraine, a film director who at once saw the dramatic possibilities and urged me to write it down. By the end of shooting I'd skimmed a couple of biographies (notably Janet Dunbar's excellent J M Barrie: the Man Behind the Image) and set about cobbling together an outline that took a good deal of dramatic licence, but was nevertheless a framework on which to hang the story as a film for television. I sent it to the BBC, where a new producer, Louis Marks, commissioned me to write it as his first production. It was at this point that Sharon Goode, my amazing researcher, tracked down Nico Llewelyn Davies [No 5], then living in happy retirement in the countryside. This precipi-tated a spate of letter-writing – over 600 between the three of us – as well as frequent Sunday visits to his home in Kent.

Nico was a treasure-trove of stories and anecdotes, moreover his cellar contained not only fine whiskey but a trunk stuffed with old family letters, photograph albums, and the unpublished typescript of his brother Peter's ‘Family Morgue' (as Peter wryly referred to it). Starting in the 1840s, the Morgue chronicles the Llewelyn Davies family's history via hundreds of letters and documents, interpolated with Peter's comments. But by the time he reached his brother George's death in 1915, Peter had become so depressed that he abandoned the project, burnt most of the original letters, and later threw himself under a train. It took a good fortnight to digest this huge compilation, along with the many other letters and papers that had not found their way into Peter's Morgue, nor the flames. And, as always, the more one read, the more complex the story became. I went to see Louis Marks, explained my dilemma and begged for more time – not just time in which to write the script, but actual screen time.

JMB in 1912

Ian Holm as JMB in The Lost Boys (1978)

Instead of ninety minutes, I felt we needed four or five hours if we were to tell the story without resorting to the simplified characters and dramatic licence of Hollywood biopics. Louis listened patiently. It would mean losing our green-lighted production dates, with no guarantee that in a year's time the whole BBC regime might not have changed for the worse. To my eternal gratitude, Louis agreed to a trilogy totalling four-and-a-half hours.

This book was something of an afterthought, written two years later in the far-too-brief span of the six months between completion and transmission. My initial idea had been to edit Peter Davies' Morgue, but Nico felt that it would require far too many footnotes. Despite Peter's wonderful comments, much of it is off the point insofar as any book about Barrie is concerned, and the overall work incomplete since it ends at George's death.

Sharon was either too modest or too wise to write a biography herself, so I took the plunge. The publishers Constable agreed to take it, believing it to be some sort of TV tie-in of so-many-thousand words. The finished typescript ended up over twice the contractual length. After a good deal of haggling, a 300-page limit was agreed upon, and a hundred pages chopped, which meant I had to end the saga somewhat abruptly at Michael's death in 1921. A second edition in 1986 allowed me to add new material in the margins without disturbing the original pagination, and this third edition permits the same. But it still leaves a wealth of material unpublished, not to mention the many new things that have turned up in the intervening years. These include all Barrie's original notes for Peter Pan – over 700, long believed lost – which I discovered in the Beinecke Library at Yale in the 1980s, and spent many weeks transcribing from Barrie's microscopic scrawl. What makes these notes so remarkable is the realisation that Barrie wrote his first draft of the play without any mention of Captain Hook at all. He didn't need a villain because he already had one: "P[eter] a demon boy (villain of story)." It was only due to the prosaic necessity of a "front-cloth scene" to give the stagehands time to change the scenery from the Never Never Land back to the Darling Nursery that Hook was conceived at all:

The Homeward Journey. The Flight by flying, the Homeward Journey by water (P[eter] with oar defending W[endy] from great birds — also attack by pirates?) P takes command of Pirate Ship.

Nina Boucicault as Peter Pan impersonating Napoleon in the 1904 production.

The front-cloth soon became a new Act V – The Pirate Ship – and the stagehands found their work had increased exponentially. Even with Hook firmly entrenched, Barrie's first instinct was to have him played by a woman: "Pirate Captain — Miss Dorothea Baird". Dorothea Baird had been cast to play Mrs Darling, and the idea of the mother-figure doubling as the ostensible villain would have been a gratifying touch, echoing one of Barrie's original titles: 'The Boy Who Hated Mothers'. In the event, Gerald du Maurier – already cast as Mr Darling – persuaded Barrie to let him play Hook as well, thus initiating a tradition that has no real thematic justification. Had Barrie conceived the play with Hook as the villain all along, I doubt that Peter Pan would have become the "terrible masterpiece" that so haunted his namesake, Peter Davies. To anyone studying Pan's evolution, these notes are essential reading, and I shall gradually post them on the internet – at www.jmbarrie.co.uk. – along with the best of the rest, including Peter's Morgue, his letters to Barrie from the Western Front (discovered at the back of a drawer in 1990), his (and Nico's) letters to Mary Hodgson (1916-1960), Nico's research letters to Sharon and me (1975-

Mr. Darling (Gerald du Maurier) and Mrs. Darling (Dorothea Baird) examining Peter's shadow in the 1904 production.

It was Anno in Italy. They'd just finished recording a rehearsal of their album, and he sounded as happy as I'd ever heard him. We talked and talked, and then he had to go. The next morning came the phone call. Anno had been killed in a car smash outside Milan with three of his friends. Like Michael, he was one month short of 21.

I don't remember ever having read Peter Pan to Anno or his brothers. I don't think he ever saw The Lost Boys, or read this book. He didn't have to. Whether I make my Barrie film remains to be seen, but yes, Anno – I do have something new to say.