I found the Flann O'Brien documentary awfully sad. The rejection of The Third Policeman by Longman's in 1940, and the destruction of most of the printed copies of At Swim-Two-Birds around the same time in a German air-raid, obviously had a crushing effect on his morale. Unable to admit to his friends that Longman's had rejected the book, he had made up stories of the manuscript blowing out the car window while driving through the countryside. Eventually in the 1960s At Swim-Two-Birds was republished, and he produced a couple of minor novels including some out-takes from The Third Policeman, but the manuscript of his masterpiece lay sadly among his papers until after his death. It is interesting that, like Douglas Adams, all his best fiction writing was done before he turned thirty (An Béal Bocht was published in 1941; he was born in 1911 - we could extend it by maybe a year or so for his three plays). He lived another quarter century as a Dublin newspaper columnist, wit and drunk - in the one surviving TV interview with him, conducted by Tim Pat Coogan in the early 1960s, he is embarrassingly inebriated.
Imagine if Graham Greene hadn't moved on from Longman's, and so had read and approved The Third Policeman for publication, as he did At Swim-Two Birds! O'Brien would have been able to get out of the civil service and become a full-time writer, years before they finally threw him out, and could have been a much greater literary, perhaps even political figure. But his defeat by Longman's reader chilled his creativity, and a voice that might have been one of Ireland's strongest was lost to the drink and smoke of the Dublin pub. He would still have been (as he himself admitted) overwhelmed by Joyce, but he would have been competing on more equal terms. As it was he had to deal with the consequences of celebrity for an early success which he was unable to repeat.
Which brings me to Douglas Adams. I've been fascinated to detect an actual plot and theme in the Secondary Phase of the radio series. The story is more Zaphod's story than anyone else's. He is the first of the major characters to speak ("I've recovered... Look, if it'll help you do what I tell you baby, imagine I've got a blaster ray in my hand." "You have got a blaster ray in your hand." "So you shouldn't have to tax your imagination too hard.") and also very nearly the last (Ford: "I just want you to know that I respect you..." Zaphod: "Great." Ford:"...just not very much, that's all.") Zaphod is the central character of most of Fits 7 and 8; the action in Fit 9 is roughly shared between him and Arthur, who then gets the lead for most of Fits 10 and 11, and then in the last episode the honours are more evenly shared again.
The story told about Zaphod is one of hubris and nemesis. He is brought to the Total Perspective Vortex where he discovers that the entire universe has been created for his benefit. The immediate effect is that he starts signing pictures of himself, "To myself with frank admiration". But pride comes before a fall, in this case the thirteen-mile fall to the surface of the planet Brontitall, and he ends up locked out of the shack of the man who really rules the Galaxy - a position Zaphod had previously believed to be filled by himself - in the rain, without a spaceship.
Arthur's story is a contrasting echo of Zaphod's in that he discovers a fifteen-mile high statue of himself, created not because of any especially heroic deed but because he has behaved as normal (ie complaining, in this case about the quality of the tea made by the Nutrimatic machine). Although he is recognised as a moral leader by the bird people, he doesn't let it go to his head, partly because they have made such a mess of it. (The man in the shack presents yet another approach to greatness, behaving as if it simply isn't there.)
Adams is obviously more sympathetic to Arthur's modest approach - he's the one who gets the romance with Lintilla, he's the one who gets our sympathy when he runs off with the spaceship at the end. But I think he is more fascinated by Zaphod. And I guess that's true of a lot of us.