The Divorce Court investigated adultery from the perspective of the injured party, giving the spectators in the courtroom and the readers of newspapers a cuckold's quick glimpses of a woman's debauchery. But Isabella's diary complicated the perspective: to hear of Henry's discovery of the journal may have put the court in the position of the horrified husband; yet to hear the diary extracts was to inhabit his wife's consciousness, to imagine adultery as an adulteress. Mrs Robinson seemed to have invited, and lovingly documented, her own disgrace. The diary's story began in 1850, when Isabella Robinson, then 37, had just moved to Edinburgh with her husband and her three sons. She was unhappy in her marriage. Henry was often away on business, manufacturing and trading iron steamboats and sugar mills, but even when he was home she felt lonely. He was "an uncongenial partner," she told her diary: "uneducated, narrow-minded, harsh-tempered, selfish, proud." While she yearned to talk about literature and politics, to write poetry, learn languages and read the latest essays on science and philosophy, he was "a man who had only a commercial life." She acknowledged, to her diary, that her frustrations were sexual as well as intellectual. As a follower of the new science of phrenology, she attributed her erotic longings to the large "organ of amativeness" at the base of her brain. On Friday, November 15 1850, Isabella attended a party in Royal Circus, near her own house in the New Town of Edinburgh. There she was introduced to her hostess, Lady Drysdale, the widow of an eminent politician; Lady Drysdale's daughter Mary; and Mary's husband, Edward Lane. The 27-year-old Mr Lane, a lawyer who had just started to train as a physician, was "handsome, lively and good-humoured," Isabella told her diary. He was "fascinating." Isabella and the family became friends. She and her sons began to visit the Lanes and Lady Drysdale almost every day, and Isabella often took trips to the coast with Edward and the children - he had a sickly son, Arthur, who he hoped would benefit from the sea air. While their boys played on the shore, Isabella and Edward discussed education and science, and read poetry to one another. Isabella was besotted. In 1852, to Isabella's dismay, she was parted from Edward. Henry had decided that the family must move south so that he could be nearer to his work in London, and in the summer he found them a villa near Reading. Isabella felt isolated in her new home, alternately listless and agitated. She confided to her diary that she worried about her too-vivid dreams, her religious doubts, her keen sexual feelings. She struggled to play the part of an obedient and loving wife, especially since she had learnt that her husband was not faithful to her: Henry had a mistress and two illegitimate daughters. He was rapacious as well. Soon after their marriage Henry had taken control of Isabella's bank account, in which she received about £500 a year from a fund settled upon her by her father, and he was trying to secure other portions of her fortune. The Robinsons" joint income, of about £1,000, put the family in the richest one per cent of the population. She was desperate to leave him, she wrote, but she knew that if she did so she would lose her sons. In mid-19th-century England, children were the property of their father. In 1853 Edward Lane qualified as a doctor and began to look for a site on which to set up a hydropathy - or water-cure - spa, a retreat for ladies and gentlemen suffering from nervous and other ailments. In 1854 he found Moor Park, a large, white 17th-century building in a wooded valley near Farnham in Surrey. Edward moved to Moor Park in the spring with Mary, their two sons and Lady Drysdale, and began to take in patients. The treatments included hot and cold baths, douches directed at the afflicted parts of a patient's body, and fresh air and exercise. Dr Lane's country retreat quickly became popular with literary and scientific types: Charles Darwin came to seek help for his digestive disorders; the novelists Georgiana Craik and Dinah Mulock were frequent guests, as were the famous phrenologist George Combe and the pioneering psychologist Alexander Bain. Isabella was thrilled that Edward was now so close at hand - Moor Park was less than an hour from her home by train. She paid a visit to the spa in July 1854. On the evening of her arrival, she told her diary, she joined the other guests in the drawing room: "Dr Lane was in the highest spirits, seated himself on the sofa I had chosen near the piano, and only left me to sing occasionally, and to speak a few words to his guests; but his eyes, his whole attention, his talk, was all mine. "I know not that I ever more enjoyed an evening," she continued. All headache was gone, all sense of sorrow; the old enchantment in that fascinating society was coming back upon me, and I felt that no one could compete in attraction with the handsome, graceful, lively, charming L. As the evening drew to a close, Mary - "his little wife, so sweet, so kind, so unsuspicious" - took Isabella up to her bedroom, and Edward soon followed: "and then they left me, but not to sleep; the bed was hard, and my spirits were far too much excited for sleep. I laid and turned till morning, and then it was late. Isabella returned to Moor Park in the autumn with her three sons: Alfred, 13, Otway, nine, and Stanley, who was five. In the morning of Sunday, October 7, Edward approached her in the house. "Dr Lane asked me to walk with him, but I thought he meant only politeness," she told her diary, "and I went to the nursery and stayed with my little pets more than an hour." He sought her out again: "He reproached me for not coming, and he bade me come away." Still she lingered with the children "but at last joined him, and he led me away and alone to our favourite haunts, taking a wider range, and a more secluded path." Edward and Isabella crossed the pretty parkland surrounding the house and climbed into the woods. It was a sunny, warm day in one of the finest autumns in years. The main path through the trees on the hill was deep in slippery pine needles and sandy mulch, the light falling through the branches in bright, broad rifts. As the path ploughed east, the valley narrowed and deepened: the river drew close on the right, the hill steepened to the left. Isabella and Edward took one of the trails that pushed up into the forest and emerged at the summit of the hill on to moors of bracken, furze and heather. The breeze carried the clean scent of Scotch pine and the marmalade tang of young Douglas firs. "At last I asked to rest," wrote Isabella, "and we sat on a plaid and read Athenaeums, chatting meanwhile. There was something unusual in his manner, something softer than usual in his tone and eye, but I knew not what it proceeded from, and chatted gaily, leading the conversation - talking of Goethe, woman's dress, and of what was becoming and suitable. Isabella's banter flitted between the intellectual and the frivolous, matters of the mind and the body, desire and propriety. "We walked on," Isabella continued, "and again seated ourselves in a glade of surpassing beauty. The sun shone warmly down upon us, the fern, yellow and brown, was stretched away beneath us, fine old trees in groups adorned the near ground, and far away gleamed the blue hills. I gave myself up to enjoyment. I leaned back against some firm dry heather bushes, and laughed and remarked as I rarely did in that presence. And then something extraordinary happened: the fantasies that Isabella had nurtured in her diary seemed to cross into life. "All at once," she wrote, "just as I was joking my companion on his want of memory, he leaned over me, and exclaimed, 'If you say that again I will kiss you." You may believe I made no opposition, for had I not dreamed of him and of this full many a time before? With the doctor's kiss, the suspense and the teasing fell away, and Isabella entered a rapturous daze. She had passed into a world in which dreams had become facts, and the facts correspondingly dreamlike. What followed I hardly remember - passionate kisses, whispered words, confessions of the past. Oh, God! I had never hoped to see this hour, or to have my part of love returned. He was nervous, and confused, and eager as myself. "At last we roused ourselves," she wrote, "and walked on happy, fearful, almost silent. We sauntered not heeding where, to a grove of pines, and there looked over another view beautiful as that on this side, but wilder. As they descended into the park they caught sight of the Brown sisters, acquaintances from Edinburgh who were staying at the house. Isabella and Edward "thought it necessary slowly to join them. They had observed nothing - we were safe. Constraining ourselves to converse, we succeeded in disarming all suspicion, and reached the house together, but late for dinner. Isabella went to her room to ready herself for the meal. She was "flushed and excited" on going down to the dining room, she said, "and neither I nor Dr L, fairly met one another's eyes or spoke." To her relief, a fellow patient - "Mr S" - sat and talked to her at the table, and afterwards she and the children, along with Edward and Mary Lane, accompanied him to the railway station. She hugged her secret to her. We were a little crowded in going, but a sense of hidden happiness and satisfaction was glowing at my heart. We chatted in returning, but of indifferent matters, and dear little innocent Mrs L--- sat behind with her fine baby asleep and laid under her cloak. Back at the house, Isabella's youngest son, Stanley, ran about her room till dusk. She then "lay down and dozed, quite overpowered with remembrance and memories." She was brought a candle to dress for the evening meal, for which she chose a gown of pale-blue silk. She "looked well," she wrote. I met his glance as I came (at the sound of the gong) to the dining room, and I knew that I was watched. After tea, "some time passed in a desultory manner." Most of the guests had gone up to the drawing room on the first floor, but Isabella hung back. I walked with Alfred in the hall, unwilling to go upstairs lest I might see him [Dr Lane] no more alone. Eventually Lady Drysdale invited her into the library, where Edward found her when he came in to the house from the stable yard. He was "cold, shivering, nervous, ill," said Isabella. Her eldest son headed upstairs to listen to one of the Misses Brown read a ghost story. Edward and Isabella went into his study. The doctor's study was a corner room, adjacent to the dining room, with windows that looked out to the river on one side and a sundial on another. In the evening, with the shutters and doors closed and a fire burning in the hearth, it was snug and warm. The walls and doors were covered with horizontal panels of red, rich-grained wood, so smooth and continuous that the doors when shut seemed to disappear, their presence betrayed only by the thin grooves cut into the panels and the rubbed shine of the doorknobs. A couple of feet behind each half-hidden door lay another door, the space between them a narrow chamber the size of a cupboard. This sealed off the study from the sounds of the house, and the house from the sounds of the study. Edward and Isabella drew near the fire. "How the evening passed I know not," wrote Isabella, as if she had lost all sense of time and self. It was full of passionate excitement, long, and clinging kisses, and nervous sensations, not unaccompanied with dread of intrusion. Yet bliss predominated. Edward, she wrote, "was particularly gentle, soothing my agitation, and never for an instant forgetting the gentleman and the kindly friend." At one point Isabella's eldest son, Alfred, knocked at the study door, interrupting their lovemaking. He told the doctor that one of his boys had asked if he would go to see him in bed. Edward went upstairs - "reluctantly," said Isabella. When he came back down she had fallen into a languid swoon. He "softly kissed my closed eyes," she wrote. I tried to raise my drooping head, but in vain. He became anxious: "at last," she wrote, "absolute dread of anyone breaking in, he advised me to go." As she left the study, Isabella wrote, "I smoothed my tumbled hair and in a few moments found myself in the drawing room, at half past nine. Fortunately, only a few of the guests were there. No one had a right to question my absence or appearance. In the drawing room, Isabella busied herself by examining a book of autographs and chatting with a fellow guest. Edward and Mary came in together, and Lady Drysdale followed soon after. What an escape I had had! What a calm appearance I could now make! General conversation followed. I turned to listen, and Dr Lane reported to Miss B--- some of the finest odes of Byron. When they went I rose too, and was gliding away, when Dr L--- gave me a warm shake, so warm that it crushed my fingers with the rings, so that I felt it for an hour. Edward pressed the rings into her flesh as if to awaken her to the force of his desire, the reality of their new compact. She was overcharged again by the memory of what had happened, her euphoria touched with fear. "Alas!" ended the entry of October 7. I slept little that night, waking, rising, dreaming - and slowly came the morn. Next morning, Isabella was exhausted. From her bedroom, she overheard Edward talking to his wife. Later he came in to her apartment to show her a long letter he had written to a prospective patient in Edinburgh. "It was a nicely written letter," she noted. She went back to bed. I lay down, wearied, exhausted, nervous. He tapped at half past 12, and bade me come down and walk: but I refused, and dozed on. Soon afterwards Mary came up to see her, and she decided to dress. Isabella "slowly went out" to join Edward. They met at the foot of the stairs, and then "sauntered out together, walking all round the grounds and by the water, yet saying little to one another, for both were weary and feeble. I named my not having slept; he said he was in pain, and could hardly get on at all. Both were agitated, confused, and nervous, and I asked him how it was he acted as he did on Sunday. Isabella suggested that they climb out of the still, close valley. I proposed leaving the grounds (as the air was hot and moist) and getting a breeze on the hill. We climbed it slowly, and I rested among the dry fern. I shall not state what followed. In declining to describe her most intimate moments, Isabella was adhering to a well-worn literary convention. The newly betrothed heroine of Fanny Burney's novel Evelina (1778) protests: "I cannot write the scene that followed, though every word is engraved in my heart." The formula implied that there were acts and feelings too sacred - or indelicate - to be committed to paper; it elided sensuality and propriety, performing a kind of trick whereby the coy heroine was enabled by silence to be at once passionate and polite - jealous of her own and her lover's privacy, respectful of her reader's finer feelings. Isabella and Edward "rose soon more composed and cheerful," and went back to the house "quickly, fearful of being too late." Over dinner, Isabella again avoided conversation with Edward: "I talked all I could to Lady Drysdale, for there were few persons present, and turned from him, leaving him to talk to Miss T--." Afterwards, she took "a nice long ride" with Edward in a carriage to the abandoned Cistercian abbey at Waverley, the Brown sisters both sitting behind them. Two days later - on Wednesday, October 10 1854, Edward Lane's 31st birthday - Isabella was due to depart. She and Edward walked around the grounds. The doctor stopped to talk to another patient, and then joined Isabella and her eldest son. They set out for the wood, "taking the usual circuit, walking through paths that I had never seen before of the greatest beauty, reaching the outer pine wood, and finally returning by Swift's cottage, and lower walk." The building known as Swift's cottage was the former home of the poet Jonathan Swift's inamorata Esther, which lay on the main path between Moor Park and Waverley Abbey. Swift had been secretary to Sir William Temple, the diplomat who had built Moor Park in the late 17th century. By 1854, the cottage was surrounded by rose trees and covered with moss, clematis and Virginia creeper; a sign outside read "Ginger beer for sale." "We talked with the utmost confidence, but somewhat more calmly," wrote Isabella. I entreated him to believe that since my marriage I had never before once in the smallest degree transgressed. He consoled me for what I had done now, and conjured me to forgive myself. He said he had always liked me, and had thought with pity of my being thrown away, as my husband was evidently unsuited to me, and was, as he could plainly see, violent tempered and unamiable. Edward reminded Isabella of the vulnerability of his own position: "We spoke of his early age, 31, the sweet unsuspicious character of his wife, rather than pain whom he would cut off his right hand." They were moving on to the subject of Isabella's unhappiness - "my often bitter misery and wish for death" - when Lady Drysdale and Mary Lane appeared. They had come to ask Isabella if she wanted them to book a fly to drive her to the railway station that evening. The doctor's wife and mother-in-law were as warm and trusting as ever: "They kindly received my determination to go away about seven, and went off again without one cold or displeased look, and yet we were walking arm-in-arm through those lonely woods and talking how earnestly." At seven o'clock, Isabella set out with Edward for Ash station in a covered cab drawn by a single horse: she and Edward sat inside the narrow carriage, and Alfred perched with the driver on top. Her younger boys were not with them - they may have gone ahead with their nurse. "I never spent so blessed an hour as the one that followed," wrote Isabella, "full of such bliss that I could willingly have died not to wake out of it again. I shall not relate ALL that passed, suffice it to say I leaned back at last in silent joy in those arms I had so often dreamed of and kissed the curls and smooth face, so radiant with beauty, that had dazzled my outward and inward vision since the first interview, November 15 1850. Edward seemed as he kissed her to melt into a dazzle of soft curls and skin, the flesh-and-blood man merging with the idol of her dreams. Between kisses, they confided in one another. "All former times were adverted to and explained," Isabella wrote. Edward told her that he had hidden his true feelings, "from prudential motives," and that the suppression had caused him "much pain." Edward "had always known I had liked him," continued Isabella, "but not the full extent of the feeling, and owned it had never been indelicately expressed. This relieved me. Heaven itself could not be more blessed than those moments. While life itself shall endure their remembrance shall not pass away from a memory charged with much suffering and little bliss; how gentle, how gentlemanly he was - how little selfish! Edward and Isabella's encounter in the cab bore a startling resemblance to the most notorious scene in the - as yet unpublished - Madame Bovary, excised by the magazine that serialised the work in 1856, in which Emma has sexual intercourse with a young clerk in a horse-drawn carriage in Rouen. Isabella's conduct was, if anything, more shameless: a child, her son, was sitting on the roof while she and Edward Lane whispered and touched inside. Edward and Isabella met again at Moor Park almost exactly a year later. In her diary, Isabella described how they sat in the drawing room till 11 in the evening of October 14 1855. An elderly female patient sat behind them on the sofa, "too deaf" to hear their conversation but loath to leave. Finally the old lady took herself up to bed. Edward, said Isabella, "after talking some little time appeared to return to his former kind feeling for me, caressed me, and tempted me, and finally, after some delay, we adjourned to the next room and spent a quarter of an hour in blissful excitement." The experience was so intense, so pleasurable and unsettling, that Isabella came close to collapse. I became nearly helpless with the effects of his presence, could hardly let him depart, wept when he bade me try to obviate consequences, and finally bade him a passionate farewell. Henry Robinson's lawyers were to suggest in court that when Dr Lane urged Isabella to "obviate consequences" he was warning her to take steps to prevent a pregnancy. Isabella was left in a state of restless melancholy. "I was alone, passion wasted and sorrowful," she wrote. Sleep was far from me that night; I tossed and dreamed and burned till morning, too weary and weak to rise. A few months later, while the Robinsons were staying in the French resort of Boulogne-sur-Mer, Isabella fell ill. As she lay in bed in a delirious fever, Henry heard her murmuring the names of other men. His suspicions aroused, he went to her desk, took out the diary, and began to read. As Henry read, the diary was transformed. It took on its own life, threatening to change what became of Isabella and those around her. Having been Isabella's accomplice, the diary became her betrayer. Its words acquired an extraordinary and unintended power.  This is an edited extract from Mrs Robinson's Disgrace by Kate Summerscale, published by Bloomsbury. To buy a copy for £14.99 (plus £1.25 p&p) go to books.telegraph.co.uk. To find out what happened to Mrs Robinson when the case went to court, read part two of our serialisation in tomorrow's Sunday Telegraph.