When BITB the play opened in New York in 1968, it took the city by storm. There had NEVER been a play about gay men and gay life before. It was a huge hit, and I've always been grateful that the movie was made with the original cast, which I saw in 1970.
At the time I thought it was searing and honest, however many unattractive elements, particularly the alcohol. I still believe this. This is not an easy play to watch.
Since then, I played Michael in a threadbare but sincere production Off Off Broadway in NYC. (Michael is a thankless role who holds the play together. Act your ass off; the audience still hates you. LOL)
Because of unavailable actors, during the 4-week performance schedule, we had a different actor playing Donald each week. The most challenging one was a guy who had done it in a production at Brooklyn College, who told me that one night, as part of their "rehearsal process," the cast rehearsed the play at the apartment of the man playing Michael, where he said they actually consumed the same amounts of alcohol as in the script! Yikes!
I used to know NY actor Ed Zang, who understudied Harold in the original production. He said that Michael was the author Mart Crowley and Harold was based on an ex, a choreographer named Howard Jeffrey, who choreographed the flop musical, "Georgy." Ed saw them seated together at the opening cast party, at the Oak Bar at the Plaza. Propped above them was a photograph of the two of them in a silver frame, with the inscription, "Can you find it in your heart to forgive me?"
Ed explained this was the inscription on the framed photo Michael gives Harold in the play. (In the play, the inscription is mentioned but never explained. When Crowley got drunk and hurt others, which happened frequently, he would send telegrams with this plea the next day.)
I met someone in L.A. years ago, who said Crowley used to live in the same apartment complex, and who said that Crowley constantly carried a notebook, in which he wrote down all the funny lines he heard.
(Sad, that none of Crowley's later plays were ever as good. I saw "The Men From the Boys" in L.A. years ago, and it really was a mess. Larry's funeral is over, Michael is now sober in AA, and there's a subplot with a younger hustler. There had been a previous production in San Francisco, seen by a friend of mine, where Larry's ghost wandered around.)
New York has changed tremendously since BITB was filmed. I feel sad seeing the old Doubleday on Fifth Avenue, now long gone. In fact, New York is no longer a particularly gay city. There just aren't that many of us left there. Which makes BITB all the more heartrending.