Has the West End changed in the past quarter century? Or is Robert Fox just having a midlife crisis? The veteran impresario has had a glamorous life as scion of one of Britain’s most lustrous theatrical dynasties. He has a string of hits to his name, from The Rocky Horror Show in 1973, via the play that launched Kenneth Branagh on to an ill-prepared world, Julian Mitchell’s Another Country, to last year’s LA revival of Wilde’s Salome, starring Al Pacino, no less. And yet . . . “My fear,” he tells me, “is that I’m going to become this sad old fart who ends up producing rather ordinary shows.”

So is Fox planning to go gentle into the good night of old fartdom? Or will he rage against the dying of his light? Judging by this interview, the answer is a combination of the two. On the one hand, Fox, now 55, has a series of furious complaints to make about the “conservatism” of British theatre. Before our meeting I had heard that he was about to sever his links with the “s**thole” that is the West End. And yet, shuttling between swagger and self-pity, he admits that this might just be the crotchetiness of a man past his prime. “I find it less fun than I used to. Maybe it’s me. Maybe it is still just as pleasurable, but I don’t find it so.”

It’s enough to bring a tear to the eye — or it might be, if Fox didn’t have a twinkle in his. He’s amusing company, he’s indiscreet — and some of his statements are as quotable as they are pleasingly ridiculous. “If the West End were the only place I made a living,” he says, “I would have had to pack up long ago and start driving minicabs.” And Prince William might work in a call centre.

For Fox is a theatrical aristocrat — his father was the agent Robin Fox, his mother the actress Angela Worthington. His brothers are the more-English-than-cream-tea actors Edward and James Fox.

As if his blood weren’t sufficiently blue, Robert then wooed his way into the Redgrave clan — although his marriage to Natasha Richardson, daughter of Vanessa, lasted just three years in the early 1990s. By then he had branched out into film production. His first project was an adaptation of the H. E. Bates story A Month by the Lake, starring his brother Edward and his mother-in-law.

More recently, he co-produced his friend Richard Eyre’s Iris Murdoch biopic, Iris , and Stephen Daldry’s Oscar-winning The Hours, starring Nicole Kidman and her fake nose. These credits may suggest a man with a taste for the stately and middlebrow — an impression bolstered by his recent West End CV, which includes ample David Hare (The Breath of Life, with Maggie Smith), Edward Albee (A Delicate Balance, with Maggie Smith, and Three Tall Women, with Maggie Smith) and Alan Bennett (The Lady in the Van, with, er, Maggie Smith). His latest production is an Albee hitherto unstaged in Britain, a philosophical mystery entitled The Lady from Dubuque. And who do you think is playing The Lady? “I love working with Maggie Smith,” says Fox.

Of course, there’s nothing stately about Smith at the top of her game. Nor about Martin McDonagh’s stage horror-story The Pillowman, the Tony award-winning revival of which Fox produced on Broadway. And Fox talks with infectious enthusiasm (the producer’s job, after all) about even the stodgiest-seeming of his productions. He is staging The Lady from Dubuque, he says, “because I love Albee’s work”. The play was pulled after 12 Broadway performances in 1980. “It’s not commercial,” Fox agrees. “It’s the kind of thing you’d expect to see at the National. But I’m not doing it just for money.” He is doing it — he always does it, he says — because “I have a romantic thing for seeing f**king wonderful plays, really well done”.

Which brings us back to Fox’s beef with the West End — which is that staging wonderful plays there is now difficult bordering on not worth the bother.

Some of his arguments are well rehearsed. Of course, unlike the revamped Broadway, where Fox increasingly works, “Leicester Square on a Friday night is one of the most unpleasant places on the planet. And if you go down Shaftesbury Avenue, you want to slit your wrists — if somebody’s not doing it for you first.” And of course, “there’s a lot of s**t on. I look down the list of West End shows, and I think, ‘What year are we in?’ Equus. Evita. The Glass Menagerie. Where are we? What time is this?”

And of course, theatre owners (including Cameron Mackintosh and Andrew Lloyd Webber) have independent producers over a barrel, “taking a disproportionate amount of money out of the production, taking all the income from the vastly overpriced programmes . . . and charging those absurd prices just for answering the phone and putting tickets in a f**king envelope. It’s an absolute scandal.”

So far, so familiar. But Fox gets more compelling when he turns his guns on the subsidised sector. The problem, he says, for independent producers, is that “actors have more opportunity to do shorter runs these days, at places like the Donmar or the Almeida”. Maggie Smith excepted, “the kind of actors who were committed to doing long runs in the West End have disappeared”.

Which is disastrous for producers, who need long runs to make their money back. Fox pines for the era of his godfather, the West End star Robert Morley. “If he was happy in a play, he’d have long lunches, then go racing in the afternoon, and in the evening he’d entertain the audience and himself hugely. And he’d stay with a play for two or three years. But nowadays people don’t want to do that.”

But surely the advent of the National Theatre, the Donmar, the Almeida are incontrovertible positives for British theatre? Fox pauses. Agonises. “It’s best I don’t answer that,” he says. Then answers it. “The way actors get to be really good is to act a lot. I think you see less really fabulous acting now because, doing plays for such short runs, actors don’t have the expertise and technique they had before.” Evidence for the prosecution, says Fox, includes the regular London visitor the Maly Theatre of St Petersburg, whose actors perform the same plays in repertory for decades on end. “And if you look at the quality of their work, as opposed to the work of companies brought together for four weeks rehearsal — well, it’s a joke what the English are doing.”

I doubt if the famously ascetic Maly Theatre ever imagined that they’d be used by a purveyor of boulevard drama as a stick to beat subsidised theatre. But Fox is a curious mix of old-school traditionalist and eat-the-rich firebrand. “There should be a tax on all hedge funds in London to pay for the National Theatre,” he says. “They should do something radical.”

It’s not that he opposes subsidy. It’s that he thinks subsidised theatre has gone soft and is stealing commercial theatre’s audiences — and its clothes.

“The Government should give the National money so that the National does things nobody else can do. But the National isn’t funded well enough to be brave. So they do what the West End does. And you get a kind of medium dumbing down. I’m not saying the work’s bad. It isn’t. But you don’t think, ‘F**k, that’s amazing! That is really out there!’ ” He hasn’t seen an “out there” show at the National since Sophie Treadwell’s Machinal in 1993.

Instead, “they end up doing Alan Bennett plays. And if there’s one person who really doesn’t need a subsidy, it’s Alan Bennett.”

So are you saying: Nicholas Hytner, get your tanks off my lawn?

“No, I’m not. Because he’s got millions of pounds of government money. I don’t have that. So what’s the point of me being on the lawn?”

Barnstorming Fox has given way to plaintive Fox again. “The thing about theatre is that everybody has quite a sick relationship with it in some way,” he says. “They love it, but they know it’s not that good for them. But they can’t stop.”

Which is why Fox, contrary to rumour, isn’t washing his hands of the West End quite yet. “I’m sure if you’d talked to [the legendary 20th-century producer] Binkie Beaumont when the Royal Court came into being, he would have been bitching and moaning about that. Because his world was over. Very few people know when to stop.”

So are Robert Fox’s frustrations with theatre just a function of age, of his eclipse by fashion, of his midlife psycho-drama? “I guess you could call it a psychodrama,” he says. “My oldest friend died at the beginning of this year. It made me think, ‘I could drop dead at any moment. Is this what I really want to be doing?’ ” And has he answered that question yet? “No,” he says, with a smile. “I’m doing a play. I’m just doing another play.”

The Lady from Dubuquepreviews at the Theatre Royal Haymarket, SW1 (0870 1451171), from tomorrow and opens on March 20

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