Three years ago this month I found the unmarked door at the back of the Grand Central pub and climbed the narrow stairs to the 50-seat Nightingale Theatre for the first time.

The theatre, once the city's best-loved fringe venue, had been closed for seven years. Now the new resident company, Prodigal Theatre, were reopening it with the first instalment of their awardwinning Tragedian Trilogy, about the life of legendary Shakespearean actor Edmund Kean.

With the noise from the pub below lending a flavour of the 19th-Century playhouse, performer Alister O'Loughlin sang, tumbled, raged, wept, and inhabited Kean with such forceful style that, when he pretended I was the actor's lover and handed me a red rose, I found it strangely easy not to snigger.

Having entered the one-chair-deep rectangle wishing for an inconspicuous back row seat, I left my first Prodigal performance with my fear of intimate theatre transformed into a craving. Ever since, I've sat in Royal Circles watching world-class performers and found myself having to fight to engage.

"I can give you the lowdown on what's a suitable price to pay for a red rose in every major European city," says Alister, who has now been touring his trilogy for six years and still manages to make every performance as fresh as each new flower.

I'm meeting Alister and his partner Miranda Henderson to talk about their three years as actor-managers of the Nightingale Theatre. In the year that the Gardner Arts Centre announced its controversial closure, the pair have just been granted full Arts Council funding. This will allow them to solidify their position as Brighton's premier developing house, and this coming Thursday they will re-launch as such with performances by the great Roger Llewellyn.

I'm also allowed a sneak preview of their startling new work, Queen Of The Slaughter.

Following last year's award-winning Brighton Festival show Ten Thousand Several Doors, it is already creating a buzz on the international circuit and will premiere here in May as part of the Brighton Fringe Festival. The Brighton Festival had the opportunity to fund it, but declined.

"The only possible justification for doing something in a theatre rather than on film," Alister tells me, "is an absolute and immediate connection with your audience in the moment.

"Hamlet could be a hero or an absolute psychotic, and the best actor will never decide it for you.

According to how the audience respond on the night the actor will walk off stage saying, Tonight, Hamlet was a hero' or Tonight, Hamlet was a bit of a w*****'. Because actually it's the audience, not the actors, who define a performance."

Whether it's playing host to actors or dancers, comedians or puppeteers, at the Nightingale Theatre intimacy between the performer and the audience is a necessity, not a choice.

Miranda and Alister met while studying at the University Of Brighton's School Of Arts in 1993, and first worked together on physical interpretations of Shakespeare. Alister had come into theatre thinking that he was going to be "this big, tall, reasonably good looking chap who would stand on the stage of the RSC and speak beautiful words beautifully". Meeting Miranda, a dancer, made him realise his body should work too.

Last year Prodigal launched the UK's first mobile playground for Parkour, the art of free running, with a dynamic outdoor piece choreographed by Miranda and featuring Alister and JP Omari of Strictly Dance Fever.

Meanwhile the company's stage work, though narrative-driven, is elevated by a subtle physical grace and unexpected moments of flight.

In Queen Of The Slaughter chairs are thrown, pianos are vaulted over and knives and swords are wielded with mesmeric speed in a chilling dance of death.

After graduating, Alister spent 18 months with DAH Teater, a group based in the former Yugoslavia which, since 1991, had been opposing the destruction of the country by creating powerful physical theatre. In 1999, when NATO bombed Belgrade and put pay to the play he was appearing in, he returned to Brighton.

"When half a million people left Belgrade in 1991, DAH Teater made a decision to stay," he says.

"They stayed so that, when the half a million people returned, they could welcome them back and tell them what had happened.

"We've also met people performing in South America who could be disappeared because of what they're doing. So when you hear people in Brighton saying it's difficult to make work, you think, mate, you don't know you're born."

With no access to a rehearsal space, Alister and Miranda used front rooms, pubs and the lawns of Preston Park. For 18 months they rehearsed at the Buddhist Centre on Tichborne Street in return for cleaning the building top to bottom. "We learned", says Miranda, "why cleaning a space before you start work isn't just about the space being clean".

Then, in 2002, the couple were offered the directorship of the Nightingale Theatre, thought for three seconds, and said yes.

That same year, while performing Part I of the Tragedian Trilogy on the Edinburgh Fringe, Alister had, to put it lightly, a surprise.

"I enter the stage singing and looking at each audience member," he explains. "This time I got halfway round and found Steven Berkoff staring me in the face." The presence of this titan of modern theatre had not gone unnoticed by Alister's audience, who were staring at Berkoff with an occasional glance at the guy on stage.

"So I delivered my opening speech directly to him in quite a confrontational way, and afterwards he burst into the dressing room shouting, Boy!

Where's that boy?' He told us he'd been interested in Kean for 30-odd years. He sent us a poem he'd written about him. It's a wonderful big long epic that he'd written on holiday."

Berkoff was duly installed as patron of Prodigal Theatre, and is now a good friend of the pair. "He's given us very rich advice and occasionally he's completely disarmed us by asking what we think he should do," says Alister. "I think he's very aware that he's kept at the top of his game for as long as he has because he's never stopped being interested in young people coming in to the profession."

On show nights The Grand Central pub downstairs doubles up as the Nightingale Theatre's reception. You don't know who's there for the performance until Alister's actorly voice sounds out above the busy bar. In the early days, sometimes only a smattering of people would detach themselves, self-consciously, from the drinkers.

On one occasion, for a charming one-man show unfortunately titled Why Love Shakespeare?, I was the only person there.

These days you're advised to book in advance, and you may spot a soap star or a famous director in the queue.

Many will be unaware, however, that the theatre functions primarily as a developing house. Tim Crouch developed An Oak Tree at The Nightingale prior to winning a Herald Angel in 2005. Joanna Neary previewed her Perrier-nominated 2005 Edinburgh set here. Zygo used the theatre to develop their Brighton Festival show The False Corpse. Brian Mitchell of The Ornate Johnsons, also regular Nightingale performers, found it an excellent testing ground for his first play, Spy.

Future development will include a new work by top contemporary playwright Mark Ravenhill, author of the international smash Shopping And F******.

Under The Nightingale's new development ladder', work from all levels of the acting profession will progress from two-minute scratches' right up to finished shows ready for touring in the region and beyond.

At the monthly scratch nights, which Alister and Miranda have been running for more than a year, three to five companies or performers present a short chunk of work in progress. The audience are asked to "pay what they can", and afterwards meet the artists in the bar to give feedback. It's a rare opportunity for everyday theatre goers to spy on the creative process, air their views, and perhaps help shape a piece of art. The next scratch night is on Sunday.

Convinced that a good venue should lend its reputation to whoever performs there, Alister and Miranda never book an unseen piece by a performer if they're unfamiliar with their work. As a result, they once had a well-known figure on the local theatre scene inform them that, "If you continue to make excellence your only criteria, you will never succeed in this town."

"Brighton is one of those places that, for a while, thought it was better at the arts than it actually was," says Miranda. "Someone called it a black hole, swallowing up funding. Not much was actually being produced, either because people were going to London to work, or because companies didn't have the support to develop or the platforms on which to get noticed."

With The Nightingale's unique focus on developing companies and new work, this is set to change.

According to Alister, the main obstacle to producing good theatre is "the near-impossibility of supporting a company of actors so they stay together for longer than four weeks before running off to take a commercial or - if they're really lucky - a guest spot on The Bill".

Most actors I interview, appearing in touring productions, will have met their fellow performers only a day before rehearsals, and faced audiences within a week. The result, as Alister puts it, is "flashes of brilliance amidst a sea of mediocrity".

Ten Thousand Several Doors, Prodigal's first Brighton Festival commission which sold out all 18 of its performances in May 2006, seemed to be composed entirely of flashes of brilliance. Started two years previously as a scratch commission called Malfi, it saw Alister and Miranda working within a large ensemble of performers.

Transporting the action of Webster's The Duchess Of Malfi from Renaissance Italy to Fifties Brighton, this superb piece of promenade theatre made use of the whole of the Nightingale, from the backstage kitchen to the pub downstairs. At one point a shutter was thrown back and the audience watched through a window as Miranda's Duchess, made her doomed escape bid through the station courtyard below.

Her brothers' corrupt court, meanwhile, had become a Brighton Rock-esque gangster fraternity, and we were fielded from scene to scene by sharpsuited heavies who dropped the H's in Webster's antiquated verse to make a sort of Clockwork Orange-style patois.

Eight months later I walk into rehearsals for Prodigal's new work in development, Queen Of The Slaughter, and am pleased to recognize each of the five person cast. Aside from Alister and Miranda, Italian Ignacio Jarquin, who played the Duchess's musical manservant, is once more at the piano.

Chris Chatfield, an expert fencer and musician who played double bass in the previous show, is apparently pretending to be a crow. Hugh Charlton, a graduate of ACT and member of Ten Thousand's chorus of bruisers, is sitting at a little round table staring at the gun in his hand.

Hugh, Alister explains later, is playing an idealist who leaves his home and goes to fight for a cause he passionately believes in.

Arriving near the front line he finds in the ruins the hope that will eventually destroy him. An international brigade of unearthly fighters play music in a piano bar and dance their tales of revolution. Over the course of a night with them the idealist takes "the fours steps to death" and is finally presented with a choice: abandon his ideology or kill his fellow man.

"My director in Serbia and me were once watching Tony Blair on the television," Alister recalls, "and she turned to me and said, That's the difference between your country and mine: we know who our enemy is. You still believe that your enemy is your friend.' Within about a year of her saying that this politician, who I had supported, was bombing the street in which Miranda and I had our flat.

"As an actor your ability to do your job is predicated on the acknowledgement that anything that one human being is capable of, another human being can do too."

Full of intoxicating live music, from Ignacio's breathtaking requiem (he is a master of belle canto, an early operatic form), to a rousing group rendition of the traditional sea shanty Blood Red Roses, Queen Of The Slaughter also involves dance, physical theatre and sparse poetic text.

Unlike Prodigal's previous works, which have tended to take Shakespearean and Jacobean tragedies as their starting points, the narrative emerged out of the rehearsal process. Early on the ensemble began to research conflicts past and present, and Alister came across the words to Zemlyanka, a song sung by the Red Army during the siege of Stalingrad: I am so far away from you, and here there are four steps to death'. That suggested a structure for the piece.

"Until now we've been a laboratory theatre company posing as a classical theatre company," says Alister, referring to drama that is created through experimentation and the evolution of ideas. "This is how we've always made work, but we've had to hide it under great big chunks of text until the timing was right."

Now Prodigal have a space and a reputation, and there's a growing audience for the kind of work they're doing - as evidenced by the success of Aurora Nova, Komedia's sister venue in Edinburgh, which has been programming outstanding international visual and dance theatre since 2001. For the past two years Komedia audiences in Brighton have been able to see cherry-pickings from the Edinburgh programme under the banners of Aurora Nova Touring and Aurora Nova South.

It is very likely that Queen Of The Slaughter, developed with a director's panel that includes the award-winning Annie Castledine (Royal Court, The National, Complicite) and dancer/choreographer Charlie Morrissey, will be part of Aurora Nova's Edinburgh programme this summer. In May, Komedia are intending to run the last weekend of the Brighton Festival Fringe in a similar style, programming five shows a day. Among them will be the premiere of Prodigal's new work which, for the first time, will not be launching at The Nightingale.

"The main purpose of The Nightingale, which is sealed now with the Arts Council funding, is development of new work and artists," says Alister.

"Prodigal is now at a point where every show we do sells out here.

That's not a healthy position for a theatre company to be in.

"We need to go up a step. And we don't want to do that by taking time and space at The Nightingale away from other companies."

Alister and Miranda are currently training another couple, Gilbert and Claire of high-octane London and Brighton-based visual theatre company Unpacked, in the art of the actormanager, which involves everything from artist booking to selling tickets on the door.

They have been extremely lucky, they say, to have encountered such authorities on theatre as Berkoff and Odin Teatret's Eugenio Barba. Roger Llewellyn, another source of much advice over the past three years, will re-launch The Nightingale on Thursday with his one-man show Sherlock Holmes: The Last Act.

They've also learnt that even those they consider to be masters are often working in an unsupported manner: they may find it easy to get a performance programmed, but it is still hard for them to find the time and space to develop their work. Linda Marlowe is just one of the big names who will be developing new work at The Nightingale this year.

"The vast majority of people in our profession spend a lot of time and energy preparing so that, when the phone rings, they can respond to the call," says Alister. "We're so diametrically opposed to that way of working that we've actually lost friends in this way.

"There's one friend that I only ever see now in adverts for Doritos.

Anything we do as Prodigal or with The Nightingale gives him a bloody nose - because he didn't have the guts to go and do it for himself."

  • Sherlock Holmes: The Last Act is at The Nightingale Theatre on Feb 16 and 17, and the next scratch night takes place on Sunday - for further details, visit www.nightingaletheatre.co.uk
  • Queen Of The Slaughter will premiere at Komedia in May.

The Dome Box Office is now selling tickets to all the Nightingale's events on 01273 709709.