Collins's family life was clandestine and complex. It was claimed that his first mistress, Caroline Graves, had met the author in mysterious circumstances. "She had accidentally fallen into the hands of a man living in a villa in Regent's Park," a family friend recalled in the 1890s. "There for many months he kept her prisoner under threats and mesmeric influence of so alarming a character that she dared not attempt to escape until, in sheer desperation, she fled from the brute who, with a poker in his hand, threatened to dash her brains out."
Doubtless the truth was rather more prosaic. Graves moved into Gloucester Place with Collins in about 1858. Ten years later she left him to marry a distiller named Joseph Clow - possibly in protest at her precarious social position, or at her lover's simultaneous relationship with another woman. Collins met his second mistress, Martha Rudd, on a trip to Norfolk in 1864, when she was 19. By 1868 he had set her up in Bolsover Street under the name of Mrs Dawson. Here she bore the novelist two children (a third, Charley, was born at Taunton Place in 1874).
This is where the domestic arrangements get really ticklish: In 1871 Graves returned to Gloucester Place, and from this point the two households lived parallel, autonomous lives. When Collins took his familial entourage on holiday to Ramsgate, he booked them into separate lodging houses.
Collins's elaborate double life had tough consequences for his descendants. "The illegitimacy did make life difficult for the family," explains the author's great-granddaughter, Faith Clarke (nee Dawson). "It stopped my aunts marrying, or having people round to the house. When I was young I was aware that there was something strange in the family history, and that people would stop talking about it when I was around. They certainly wouldn't discuss it in my presence." It was only when her husband, William Clarke, began researching his book The Secret Life of Wilkie Collins that she learnt the details of her family's concealed past.
"The touch that's always appealed to me is that my surname, Dawson, is fictional. Nobody knows why he chose it. He might even have taken it from the name of the doctor in The Woman in White." Clarke doesn't blame Collins for his unwillingness to make an honest woman of her great-grandmother. "All I've read and heard about him first-hand from my family has convinced me that he was a warm, generous man, and very sympathetic towards children."
Which brings us to Collins's mock-marriage with the 11-year-old Anne le Poer Wynne, nicknamed Nannie. The correspondence between the young girl and the 61-year-old novelist began in 1885, when she and her widowed mother were living in the quiet London suburb of Little Venice. Francis Beard, who was doctor to all three, may have introduced them. Over the next four years Collins wrote to Nannie twice a month, maintaining the conceit that they were a married couple. "Dear and admirable Mrs Collins," he enthused, "Mia sposa adorata." They swapped photographs, and Nannie sent her admirer flowers and Christmas cards.
A late-20th-century social worker casting an eye over these letters would probably argue for an exclusion order to be slapped on their author sharpish. Especially, perhaps, in the light of Collins's advice to Nannie that she combat the effects of hot weather by adopting "the costume of a late Queen of the Sandwich Islands - a hat and feathers and nothing else".
William Clarke, who has co-edited the letters, is sceptical about the possibility of any Dodgsonian irregularities in this relationship. Wynne family descendants have assured him that Nannie's mother was well aware of the correspondence, and that she accompanied her daughter on visits to Gloucester Place. "It's a charming correspondence. I don't think it has any sexual overtones," he argues - though his publisher is putting a rather different spin on the story.
Heart and Science contains a portrait of a relationship between an older man and a young girl that reads like a Gothicised account of Collins's Little Venice mock-romance. Its principal villain is Dr Benjulia, a sadistic vivisectionist who keeps a monkey in his coat and enjoys a strange intimacy with a precocious 10-year-old named Zo. "One of his favourite recreations was tickling her.... He put two of his big soft finger-tips over her spine, just below the back of her neck, and pressed on the place. Zo started and wriggled under the touch. He observed her with as serious an interest as if he had been conducting a medical experiment...." Of course the reader is led to believe that if Zo is ever foolish enough to enter Dr Benjulia's windowless laboratory, she will be dissected in a jiffy.
The official debut this week of Iolani; or Tahiti as It Was provides another gloss on this aspect of Collins's fiction. The novel - written during office hours when Collins was apprenticed to a tea merchant in the Strand - is set in Polynesia before European contact. It's the story of a high priest fixated upon the idea of sacrificing his illegitimate child to the gods. The clandestine murder of unwanted children is a theme that Victorian readers would have found creepily familiar. (One contemporary newspaper report suggested that "an uneasy persuasion pervades the public that their masters connive, to a frightful extent, in the surreptitious disposal of the bodies of stillborn and illegitimate children, packed like lumber into cheap coffins".)
Iolani demonstrates that even in his apprentice work Collins was formulating the idea that would dominate his mature output, and perhaps informed his disinclination to officialise his family relationships. The domestic sphere, the fiction argued, could easily become a source of unease and danger. "The secret theatre of home", he called it: a stage upon which dark family dramas were played out, where atrocities might be committed without the neighbours suspecting a thing. As Henry James commented, "To Mr Collins belongs the credit of having introduced into fiction those most mysterious of mysteries, the mysteries which are at our own doors."
The households featured in his novels are invariably sinister, freakish institutions: the domestic spaces of The Woman in White (1860) are occupied by a mouse-fancying, bon-bon-guzzling Italian gangster, a moustached lady, an effeminate hypochondriac who locks himself away with his collection of etchings, and his French valet. In Poor Miss Finch (1872), the congenitally blind heroine shares her home with the widow of a South American revolutionary and a pair of identical twins - one a suave landscape artist and the other a mimsy epileptic who has turned himself blue by drinking silver nitrate.
The Law and the Lady (1875) offers the oddest domestic scene in the Collins canon. In this novel the newly wed Valeria Woodville's crusade to clear her husband's name of murder forces her to pay several visits to the home of a paraplegic maniac named Miserrimus Dexter. Dexter is as seductively weird as any character in fiction. When not torturing his transvestite servant, Ariel, with a bizarre S & M game involving string and fairy-cakes, or careering around the house in his wheelchair declaring himself to be Napoleon, he is pan-frying exotic mushrooms for the heroine or making passes at her by leaping into her lap. This kind of thing just doesn't happen in George Eliot.
And unlike his friend and occasional collaborator Charles Dickens, Collins rarely wrote of the home as that Christmas-card-cosy place where reformed misers handed out geese to disabled children. Home was where your wife might murder you with poisoned lemonade; where a letter might arrive to tell you that your father is not who he has claimed to be; where your doctor might watch you slowly die to satisfy his scientific curiosity. Joseph Conrad had to send his hero down the Congo to encounter the worst forms of human depravity. Collins, we now know, looked for it in an imaginary Tahiti. His published work suggests that he eventually found it on Acacia Avenue. A strange conclusion for a man whose domestic life seems to have given him the best of both worlds.
`Iolani; or Tahiti as It Was' is published by Princeton University Press on Tuesday. `The Letters of Wilkie Collins' are published by Macmillan in June. Matthew Sweet's new critical edition of `The Woman in White' is published by Penguin Classics in October.
Sentimental nonsense or the predatory workings of a dubious mind? Wilkie Collins was 64, `Nannie' 14 when he wrote this to her:
Dearest Mrs Wilkie
Don't bully me. Mother-in-law will tell you that I am already prostrate. Besides, I don't approve of your conduct since I have been away. I hear you have got tall. Have you forgotten that I am short? News has also reached me that you have got a waist. Have I got a waist? And, greatest disappointment to me of all, I am positively assured that your back hair is on the top of your head. My hair hangs on my shoulders. I have not had my hair cut for the last four months to please you. A good wife follows her husband's example. What right have you to hide the top of your head from Me. I have a right to see (and, if I like, admire) the top of your head. There may be one excuse for you. Are you getting bald on the top of your head? If that is the case, I pity and forgive you. When I come to see you, I will bring with me "Mrs Allen's Hair Restorer" and rub it in myself. But don't allude to "Galantine and Truffles" - your mother, your excellent mother, will tell you why. With all your faults, I love and adore you. WC