BIOGRAPHY: Constance: The Tragic and Scandalous Life of Mrs Oscar Wilde,By Franny Moyle ,John Murray, 374pp. £20

THE MOST MOVING experience I had in researching the background for my play The Secret Fall of Constance Wilde, about the wife of Oscar Wilde, was reading some of Constance's handwritten letters. I became aware of the deterioration of the writing over the decades. It only gradually dawned upon me that I was actually "reading" the progression of the "creeping paralysis" that eventually killed her in April 1898, just short of her 40th birthday.

Franny Moyle has read far more of Constance’s letters than I have (more than 300, apparently), and her book now replaces, and sometimes corrects, the earlier ones on Mrs Wilde by Anne Clark Amor and Joyce Bentley. For example, she offers more detail than ever before about the death of Constance, who was always sickly and prone to depression but then also began to develop a mysterious progressive paralysis. Against the advice of her own doctors and friends Constance submitted herself for surgical treatment at an Italian clinic, and died as a result. This tragic decision is typical of the woman who was risking everything for the remote possibility of a normal life with her two children. The risk-taking with a doctor who had a dubious reputation was also typical, as was the bravery to undertake the journey alone.

The book opens a little more than three years earlier, in London, with the dramatic delivery of a famous letter from Oscar to Constance. He was living at the Avondale Hotel and she at the family home on Tite Street, in Chelsea, a domestic arrangement that said all about the nature of their marriage. “Dear Constance,” he wrote, “I am coming to see you at nine o’clock. Please be in – it is important. Ever yours, Oscar.”

At the very point of his conquest of the West End with the great success of both An Ideal Husbandand The Importance of Being Earnest,Wilde was about to make his spectacular crash to the bottom. This was the signal behind the panic of his letter. Moyle uses this incident to provide a wonderfully detailed setting of the London of the day and its weather, of the trendy Wilde house with its aesthetic decorations, of the style and values of late Victorian society and of the characters and backgrounds of the two principals in the drama about to take place. It is a model of how to create context at the start of a biography.

It is entirely possible that Constance and Oscar first met in Dublin, as Constance’s mother, Ada, was a Dubliner whose mother lived on Ely Place. In turn, her brother lived around the corner, on Merrion Square, a close neighbour of the Wildes. It is a pity that this Anglo-Irish network isn’t given more air in the book. There is little doubt that Wilde’s Irishness, like Shaw’s, contributed to his subversive, comic treatment of English society and to the way he created a public persona that stood at an extravagant angle to the English establishment.

One would like to know more about Constance’s Irish cousins. Certainly, Constance was also a rebel and deliberately took avenues that led her away from established English mores. But whether this had anything to do with her Anglo-Irish connections is another matter.

Before her involvement with Wilde, Constance was already a radical young woman. She was drawn to the Aesthetic Movement, to progressive art and to its disreputable followers, as at the Grosvenor Gallery, for example. She was also interested in socialism, admittedly tinged with Christian morality, and, finally, in the new feminism of the final decades of the 19th century. Franny Moyle is very good on all of this, and presents a full portrait of an intelligent, committed young woman trying to make an independent life for herself in a London still dominated by men. “If I eventually do not marry,” Constance wrote, “I shall do something.”

She did marry, of course, and for the early years, at least, of the marriage, she was an equal partner with Oscar. They were the celebrity couple of the day in an age, like ours, smitten by celebrity, setting the lead for society in dress, interior decoration and advanced ideas, with at least a semblance of gender equality on display. It didn’t last.

Moyle makes an interesting case that Constance was drawn to close, intimate relations with older women and that it was with these women that she came to express herself most fully. This biography claims that these relationships were a kind of replacement of the maternal relationship that Constance never had with her own mother, Ada.

Lady Mount Temple provided a retreat near Torquay, on the coast, and, incidentally, is also the source of many of the letters published, for the first time, in this book. Oscar’s mother, Speranza, the outrageous, colourful Lady Wilde, was always close to Constance and shared her radical political opinions. So did Lady Sandhurst, who ran as a Liberal local-government candidate in 1889, with Constance as an activist in her campaign. They won the election, but lost the seat because English law was not yet ready for female public representatives. Moyle is surely right that Oscar Wilde, then editing the Woman’s World magazine, was politically radicalised by his wife at this point in his life.

Wilde is the shadow across this biography. I remember working on my play, and speculating with a gay friend about when Constance realised that she had married a bisexual. My friend said she knew from the beginning. I think he was right in the sense that knowledge is not always a conscious thing; it often resides in the secrecy of the human heart.

Franny Moyle tells the poignant story of Constance in the aftermath of Wilde’s trials and imprisonment, and of her brave attempts to keep in contact with him despite her suffering. When she died he inherited £150 a year from her will, but it meant little as he was dead himself within two years.

Thomas Kilroy is a playwright and novelist . His play The Secret Fall of Constance Wildepremiered at the Abbey Theatre in 1997