Talking to Ronald Harwood the Friday before his BAFTA success with The Diving Bell And The Butterfly, I thought I might detect a frisson of excitement in the air. The man, however, admits he is still "bombed out" less than 48 hours since he returned from Hollywood to attend the Oscar nominees lunch for the same film at the Beverly Hills Hilton. Harwood won an Oscar for his adaptation of The Pianist in 2002, so does he feel as nervous this time around?

"It's very exciting, but quite a different feeling from being nervous. After being nominated three times I'd probably say you're more a bit tense. With The Pianist I think I was a 100-1 outside chance and with those odds you can't really predict if you'll win or not. It'd be silly to do it. You just can't forecast the Oscars."

One of the reasons the South African-born writer, who has made London his home for 57 years, has returned to England is because he has a play opening at Watford Palace Theatre. An English Tragedy, which is based on real-life events, adds to his repertoire of World War Two stories, which include Operation Daybreak The Statement, The Pianist and Taking Sides. The play follows the trial of Nazi broadcaster John Amery, son of British politician Leo Amery, who was arrested for treason and returned to London at the end of the war to stand trial.

Ronald, 73, tells me he's had an interest in the story since 1966. "I read Rebecca West's The Meaning of Treason at the time and thought it would make a good play. It's such a haunting story."

So why the gap between first reading it and writing the play itself?

"You can't guess the gestation period of a play. The Dresser took 12 years to write. I didn't have a solution to An English Tragedy. Then I read an article that revealed something about the family and then I knew how to do the play."

Watford Palace artistic director Brigid Larmour says: "It's fantastic working with Ronald on this important and timely piece. He is a pleasure to have around with his charm, wit and intelligence. We hope that the success of The Diving Bell and the Butterfly might encourage cinema goers who don't normally go to the theatre to come to Watford Palace."

As a member of the Screenwriters Guild in America, we talked about his involvement in the writers' strike and on BAFTA night, he was happy to announce the end of the conflict between producers and writers in the US. As president of the English PEN Club, chairman of the Royal Society of Literature and president of the Royal Literary Fund, Harwood is also a campaigner for the rights of UK writers. He says the Brits don't have as hard a time of it as their American cousins, though other members of a film crew do.

"They don't realise there are so many other people involved in making a film - actors, cinematographers and the crew members, not just directors and writers, and that's a problem."

Despite his fame stateside, Ronald's plays have not always had the West End profile that many feel they deserve. Is this because regional theatres are prepared to be more experimental or challenging?

He says: "I guess that's true. London has a commercial and economic problem and in regional theatre it's a little freer. I hate the word experiment, I prefer to say directors can be a little more daring."

REVIEW: AN ENGLISH TRAGEDY

THE ARRIVAL of an Oscar-winning playwright in our midst brought more than the usual crowd of critics including several national newspapers to Watford Palace theatre on Monday night along with a fair sprinking of celebity talent. I happened to spot a couple of Lark Rise To Candleford stars straight off. Olivia Grant (Closer, Stardust), who plays Lady Adelaide Midwinter in the ten-part TV adaptation of Flora Thompson's book and John Dagleish (Richard III, Moliere), who plays Alf Arless. I asked them what had brought them to Watford. John told me Di Trevis had directed his last production of Moliere. Olivia added that Lark Rise is also cast by Sarah Trevis, Di's sister, so it's obviously a family affair. I also found time to clock Anna Carteret (Juliet Bravo) and Will Young, and Tom Wilkinson (Michael Clayton) sitting a couple of rows in front.

With the Oscars looming this weekend, it was gratfying to see Ronald Harwood in attendance. Having already gleaned the BAFTA for best adapted screenplay with The Diving Bell and The Butterfly it is hoped he might score again at the imminent Academy Awards. For the time being, however, Harwood has certainly made an impression on this particular theatre-goer. His new play An English Tragedy, which has its world premiere at Watford Palace, opens with the image of a large red and sllver swastika and the sound of Nazi propaganda broadast over the airwaves. The production wastes no time in getting its message across.

Although on one level it concerns the trial of John Amery, who was executed for treason at the close of World War Two, An English Tragedy also raises the debate on what it meant to be English at the time. The trial is used as a historical framework in which Harwood can discuss issues of nationality, identity, individuality, collectivism and social responsibility. As we learn from his defence council, Amery failed to respond appropriately to other people all the way through his relatively short life. He died aged only 33. At the request of his lawyer, John's parents, Leo and Florence (Bryddie) Amery, agree to have a psychiatrist examine their son's mental condition. It is hoped that by shedding light on his state of mind, they might help clear their son, but unwittingly we see how their denial that he has any real problems to deal with has contributed to his lack of conscience and empathy for other human beings. The council hears reports of housemasters and tutors who failed to tame John during his youth. All involved talk of John's failure to be responsible for his actions and yet Leo and Bryddie continue to make excuses for him. They bare blind to how their own behaviour might have shaped him. As we see from their interaction with their son, their clipped manners and tendency to put their heads in the sand have contributed to his unfettered impulsiveness.

Despite the heaviness of the subject matter, corporal punishment, anti-Semitism and how a lack of pastoral care can have devastating effects on a child with suspected autistic tendencies, the play is full of humour and acerbic wit. It does not excuse John of his actions but rather examines the process by which his anti-social behaviour was allowed to go unchecked. Even as the gallows looms Amery senior feels he has to ask his son if he might give him a hug and John's laconic reply is addressed to his childhood toy rather than his father: "Teddy thinks not," he replies and the audience is left to ponder on how far this nation has come since then. It is a peculiarly English tragedy indeed.

Until Saturday, March 8.