The last time I met David Hare was in the green room at the Hay literary festival. I had just finished my public humiliation, so was feeling light and joyous; he was just about to go to his, so he was even lighter and fuller of joy. If Hare was born to do anything, it was to sit on a podium and talk about his oeuvre. He is terrifyingly fluent, spookily cogent, like a livestock auctioneer reciting The Waste Land. Do you enjoy public speaking, I asked? His answer could be digested to: “It depends.”

He told me a story. He’d gone to Australia to give a lecture on English theatre and his work. Australia is quite a long way to go for a public appearance. “I did the talk and then asked if there were any questions. A single hand went up at the back. ‘Yes, gentleman there.’ ‘Mr Hare, have you ever met Diana Rigg?’ ‘Well, theatre is quite a small world, and everybody tends to know everybody else, and, actually, I have met Diana Rigg. Are there any other questions?’ Another hand went up. ‘Gentleman there.’ ‘What’s she like?’”

He told the anecdote with impeccable timing – of course, he knew it was funny. But there was no sense of self-deprecation, and there was the distinct implication this was a parable on the sort of hill that playwrights have to surmount for the sake of their art.

On he went to the packed tent, and I repeated the story to Michael Gambon, who was sitting in the front row. Hare spoke rivetingly about his 2003 National Theatre play The Permanent Way, and that’s an example of his loquacious wizardry: being able to keep 500 literary groupies spellbound describing a theatre production about railway time-tables. Then it was time for questions, and Gambon hoisted an etiolated hand, like an orang-utan reaching for a banana, and asked: “As you’re such an important man in the theatre, Mr Hare, did you ever meet Diana Rigg?”

The audience giggled, I sniggered and Hare smiled the thin, humourless smile of the classics teacher humouring vulgar boys while trying to stuff eternal truths into their thankless heads.

Now I’m sitting in the basement bar of the Royal Court theatre, waiting to interview Hare, who is here for the rehearsals of his latest play, The Vertical Hour. He is led in by a press officer. He looks tired and is unshaven and shabby, in a set-aside, corduroy way, which is unusual: being married to the fashion designer Nicole Farhi, he usually brushes up sharp, sporting a nice collection of leather jackets, a look that’s best described as socialist-dapper.

He sits and orders tea, earl grey, and sets off at a conversational canter around how godawful theatre critics are. “I know you’ve written about this – everything is either simply dreadful or the best thing they’ve seen in their lives. It’s ridiculous. They used to be much better, more knowledgeable, and wrote much more. They wrote things like: ‘Mr Hare attempted to ... etc, etc.’ It was a proper discussion of the play: ‘Some parts were successful, some less so.’” Actually, it all sounds rather boring – more notes for writers and directors than information or entertainment for newspaper readers.

Everyone I spoke to about Hare said two things: whatever you do, don’t quote me, use my name or tell him you’ve spoken to me; then, he simply cannot take criticism. One director added, not just criticism – even the merest note of dissent, whiff of contradiction. He suffers the thinnest skin of anyone in the theatre; he remembers every syllable of every slight. He never forgets, and he doesn’t know how to deal with it, but don’t say I said so.

“I’m only doing one piece of publicity for the play, so I thought it might as well be The Sunday Times, and it should be you,” he announced.

Now, this obviously puts me in an invidious position. It’s flattering to be thought of by anyone, but especially by a leading knight of the theatre and prince of the written word; but, as a journalist and a critic, it implies I am a soft touch, a cheap date, which may well be true. We know each other a little, we’ve had dinner together, we share mutual friends, our partners get on and I’m a fan. I’ve liked most of what he’s done in the past, some of it very much indeed, like Amy’s View and Skylight. And Fan Shen, a 1970s piece of agitprop about China that I saw at the ICA as a student, is still one of my most memorable theatrical experiences.

Yet there are things about his work I am less keen on. I remember meeting him on an escalator at Tate Modern, and him saying, “Heard you wrote a very good piece in the paper – I’m afraid I didn’t read it. After Pravda [the 1985 thinly disguised portrait of a press baron he co-wrote with Howard Brenton], I really can’t read the Murdoch press.” Seeing that, at the time, he was writing a column for The Sunday Telegraph, I mentioned that that was rather like the pot calling the kettle Conrad. So, anyway, perhaps he’ll never read this and won’t hate me for ever.

So, Mr Hare, tell me about The Vertical Hour. “It’s a play about a liberal intellectual who supports the war.” You mean like Nick Cohen or Christopher Hitchens? “Actually, I was thinking more of Michael Ignatieff.” Really, the long navel-gazer who, even for a Canadian, has had a conspicuous humour bypass? Why would you care what he thinks? The play first appeared on Broadway at the end of 2006, and was a qualified success. Sources close to the production told me that while Bill Nighy had been rivetingly brilliant, Julianne Moore had had trouble grasping and inhabiting the text.

This is Hare’s second play about the war in Iraq. The first one, Stuff Happens, was a reciting of the record by actors playing politicians, repeating excerpts from speeches straight at the audience. I particularly disliked it: I thought it was patronising, boring, unsubtle to the point of crass naivety. But, of course, I didn’t say that. I said I liked the bits that weren’t gleaned from the record, the bits that were sort of playwriting. Hare does exhaustive research for his pieces.“I read 40 books for Stuff Happens; my researcher read dozens more. You know, this is the only record of what actually happened, of how we got to the war, to appear anywhere.”

Don’t you think that it was a bit like singing to the choir? The National Theatre audience just came in to agree with you. “No.” Hare is certain that a new, younger audience were attracted to the politics of the play. There is, I must admit, something admirable about the commitment of this method school of playwriting, the complete immersion in the subject, but it makes a sort of Norman Rockwell evening of social realism, with blinding detail, so you end up admiring the effort rather than the message. Did he mind the label political theatre? He sits back. This is familiar territory, and he asks: “What isn’t political theatre? Macbeth is political theatre.” Yes, but Shakespeare didn’t read 40 books of medieval Scottish history, he didn’t use direct quotes and, actually, Macbeth is a historical travesty, written to ingratiate himself with James I. Don't you think you confused facts with the truth?" "No," he repeats emphatically. "The facts are important, they're what make up the truth."

But do you think people are going to be putting on Stuff Happens in 100 years’ time, when the war is a forgotten footnote? “I hope it will still be relevant as a study in power. There are two sorts of playwright: those that use events and the real world, and those that just write out of their heads.” He says that most theatre bores him, most plays are terrible, partly because they’re not about anything interesting. “I’m not interested in theatre that’s just some stream of consciousness.” He doesn’t name names, but I’m guessing we’re not a million miles from Samuel Beckett.

Stephen Fry pointed out that the world can be split between people who divide the world in half and those who don’t. Hare belongs in the former category. The two sorts of playwright are Shakespearian or Chekhovian. Shakespeare, Hare says, puts everything on stage. If there’s a battle, you see it. He shows it all. In Chekhov, everything happens off stage. His characters react to stuff you never see; it’s always just happened or is just about to happen, but nothing actually ever happens in Chekhov. “I’m with Shakespeare,” he says, in case there was any doubt.

Do you ever use your plays to settle arguments in your head? Are they esprit d’escalier, where you get the last line and take the high ground? “No, never.” Oh yes he does, says the source close to The Vertical Hour: one of the characters in it is obviously him, and he’s not Shakespearian, he’s Shavian – his characters are the vessel into which he pours some brilliant arguments and inspired ideas. His Via Dolorosa, a monologue, delivered by himself, about a theatrical journey through Israel and Palestine, was memorable theatre, and thoughtful politically, but, most of all, it was great humanity and a svelte performance.

For some time, I have thought that while British theatre has a sparkling repertoire of actors and – despite the number of musicals – an impressive canon of senior playwrights, where it’s essentially thin, not to say famished, is in its directors. Theatre director is a very new profession and, with a few exceptions, the ones we’ve got now are pretty desperate. Most of the bad productions you see are the fault of banal direction. Do you want to comment, I ask? “No,” he says, then pauses and adds: “There are two sorts of director – the Peter Brook ones, who do a lot of workshops and games and group therapy away from the text, and the ones who are more like Joan Littlewood.”

Littlewood was the strident, opinionated and adored director who ran London’s Stratford East theatre in the manner of Brecht’s Berliner Ensemble. Brendan Behan’s plays were premiered there, and a generation of actors and writers started there, among them Lionel Bart, Richard Harris, Ken Russell and Barbara Windsor. Its most successful production was Oh, What a Lovely War!, adapted, ironically, from a book written by Alan Clark, who took a 50-quid fee rather than a royalty because a bunch of arty commies would never make any money.

Whereas Brook is currently the presiding angel of the South Bank and Shaftesbury Avenue, there is very little Stratford East visible in the theatre at present, I suggest, theatre with a collective power, in which the cast raises the hairs on your nape. “I went to see something recently that was a brilliantly Littlewoodesque production,” Hare says. “I think it’s the best thing on – Billy Elliot.” (It is directed by Stephen Daldry, who also directed Hare in Via Dolorosa; Hare wrote the screenplay for Daldry’s film The Hours.) Doesn’t he find film disappointing at the moment? “I suppose a lot of it is, but the thing is that American television is so good. We took Stuff Happens to Los Angeles – there were so many marvellous actors to cast from. Television drama is very strong over there. I’ve got a box of DVDs someone told me to watch, a thing called The Wire – they say it’s very good.” “It’s fantastic, you’ll love it.”

“I think that’s just about it,” he says suddenly. “That’s enough.” As we get up to go, I ask: “Do you ever get angry when you write. Is anger part of it?” He waits and thinks, then looks away. “Yes, deep anger, mostly directed at myself, real self-loathing. I used to suffer from that, less now, but when I started, it was very strong.” And he tails off.

As we reach the foyer, Hare is going to a cast and production bonding party. I ask for his phone number to check stuff. “You don’t take notes,” he says, “or use a recorder.” No. “So, will you go away and write this up now?” No, I’ll wait a couple of weeks. “Well, how will you remember?” By remembering. “But will it sound like me?” No, it will sound like me having talked to you. There are two sorts of journalists.

The Vertical Hour previews at the Royal Court, SW1, from Thursday

Editor's choice

• U2 at Nou Camp Stadium, Barcelona
• The 50 Best Movie Villains
• The 15 golden rules of theatre etiquette