A week later, we're sitting in a modest dressing room outside a vast auditorium in Newark, waiting for Judy.
There's her agent, David Begelman, her dresser, her assistant, and a blond kid with a dispatch case in his lap; also me, the fly on the wall.
The door opens and a short, fat, middle-aged woman appears in a buttoned-up overcoat and a babushka around her head. She could be the cleaning lady without the mop. It takes a while to realise this is Judy Garland.
I still don't recognise her, but I recognise the change of atmosphere. A chair is produced. White wine is poured. There's a sudden spurt of camaraderie. No one mentions the concert is supposed to begin in 15 minutes.
Judy starts singing an old barber shop quartet song. Begelman harmonises. Everybody joins in.
It reminds me of forced cheeriness around a hospital bed.
Judy sips a little wine: "I'm not supposed to drink this." The blond kid opens the dispatch case. Judy studies several stacks of coloured pills and chooses two.
An hour later I'm alone, hiding in the shadows of the huge backstage area. Out front are 4000 restless people. Judy appears backstage in a funny costume - a tiny figure in red-and-white striped shorts, a glittery blue blouse, and a star-spangled top hat. She looks like the cleaning lady in a funny costume. I'm almost feeling sorry for her.
The overture begins, a long selection of Garland favourites. Judy stands behind the curtain, silent, unmoving. Something remarkable is happening. Her legs are getting longer, her body slimmer. A neck appears where there was no neck before.
As the overture ends, she opens the curtain and strolls out on the stage, and - dear God - it's Judy Garland singing Chicago and knocking them dead! I have never in my life seen such command of the stage, such total communion with an audience.
Twelve weeks later the rewrite is finished (well, for the moment), and we're off to London to make a movie.
The producers rent a historic country house outside the city for Judy. She stays there for two hours and decides she doesn't like it. Okay, they'll find her a hotel suite in London.
Next day, the real estate lady calls with a bill for £4700 for the damages. Damages? The fire in the reception hall. The ruined rug. The door off its hinges. The broken original leaded glass window. How did all this happen in two hours? Nobody knows. Nobody ever finds out.
Every morning, Judy gets picked up and driven to Shepperton Studios where our film, now called I Could Go on Singing, is being shot.
One morning Judy does not arrive. We wait. Ronnie Neame, the distinguished English director, waits. Dirk Bogarde, Judy's co-star, waits. The cameraman waits. The sound guys wait. Costumiers wait. The girl with the tea trolley waits. The writer waits with new rewrites. Producers pace the floor.
It costs $50,000 a day to keep the doors of the studio open. That's real money in 1962.
At four in the afternoon, Judy appears. She has spent the day at a hospital singing to her driver's sick child. Is this kindness or craziness? Whatever it is, it has cost us a day from a tight schedule. From then on, every morning there's a tense wait until Judy's car pulls up to the studio gate.
After two more weeks of working in my little office, the producers come to me with bad news. Judy has fired me. Why? Nobody knows. But how can she fire me? Well, it's in her contract. You never told me. We never imagined that she would ... But she did.
Now what do I do? They have a suggestion. What if they pretend to hire a new writer and I continue rewriting secretly away from the studio. I don't feel good about this. Look, the producers say, we're all friends. We'll make it work.
They guarantee I'll still get my writer credit. So, okay, I'm secretly rewriting my rewrite of the original writer's script, adding more of Judy's wit and charm.
Meanwhile, down at the studio, life with Judy proceeds: She tries to fire Ronnie Neame, the director. It's not in her contract, but Ronnie Neame doesn't understand her, she wants him gone. The crew announces that if Neame goes, they'll go too. Neame stays; Judy returns to work. Another day lost.
Occasionally I sneak into the studio to talk over the next day's shooting with the director. Neame shows me some of the uncut dailies from the film. I marvel at Judy's screen presence, even in the out-takes. What a good actress she is. When she works, she works hard.
A week later, the producers, along with the director, appear at my hotel. Two nights ago Judy called Frank Sinatra in Australia. "I can't take it any more, I'm saying goodbye." Sinatra called Hollywood, Hollywood called New York, New York called London, the producers called the guard outside Judy's hotel suite, who breaks in to find her semi-conscious, pill bottles everywhere.
Judy is taken to a hospital and pumped out. She'll live; production is suspended. The question is: when will she come back to work? Does this sound heartless? Yes, it is heartless. When you are making a film, nothing in the whole world matters, except making that film.
Judy's psychiatrist calls the producers. "You evil corrupt monsters are destroying this poor abused girl." She's in no condition to work. The producers beg: We have a picture to finish, we'll accommodate her, shorter hours, rest periods. If she could just come back for a few days.
"Well," says the psychiatrist," how many days is a few?"
The psychiatrist is now Judy's agent. He's negotiating. She owes us 16 days. The psychiatrist says: "She'll do 10." All this is totally bizarre and even comedic. But the comedy stops with me. The producers and the director give me my orders: You have to cut, cut, cut, then paste, combine, change, and add continuity, so the story still makes sense - and you have the weekend to do it.
Trying not to panic, I sit down at the typewriter. I'll have to work without sleep for a couple of nights. The new shortened script still has Judy Garland's wit and charm, and even, here and there, a touch of poignancy.
Judy comes back to the studio; production is resumed.
So far, millions of dollars have been spent shooting scenes that are just strips of film in an editing barrel. Judy has not recorded the songs. Until Judy Garland sings, there's no picture.
She's scheduled to record on the last day of production. Trying not to panic, one of the producers suggests we could create some bogus screw-up that would encourage Judy to record earlier. Then we could get rid of her. The writer could write something to patch it all together. The other producer points out that Judy may be crazy, but she's crazy like a fox. She will never record the songs until the end.
We have to keep her happy for 10 more days.The producers take her to dinner. She's in a good mood. They leave her laughing. At three in the morning she calls one of the producers and tells him to tell the other producer that she's not coming in again "until you start treating me like a goddamn f------ lady". The producers panic. But the next morning Judy comes in as though nothing has happened.
Finally, Judy sings. It's brilliant. Full of emotion. Endlessly moving. Super professional. And so we have a picture. Will it be any good? We're way beyond that. We have a picture.
The film gets respectable reviews, though modest box office returns. The producers' partnership breaks up. Ronnie Neame goes on to make big Hollywood films. Judy never made another film. She got a television series but it crashed and burned. She continued singing in major theatres, and then in smaller and smaller venues. She was rumoured to be sick.
I saw a picture of her at her last concert in 1969. She looks like a wizened old woman. Correction: she looks like a gallant wizened old woman. Then she was dead at 47.