But there is the question of the ring. Arthur wants her to wear something, however discreet, on her finger – it does not matter which – to send him a secret message whenever they are in one another's company. Jean does not favour this idea. Men give rings to three categories of women: wife, mistress, fiancée. She is none of these, and will wear no such ring. She will never be a mistress; Arthur already has a wife; nor is she, can she be, a fiancée. To be a fiancée is to say: I am waiting for his wife to die. There were such understandings between couples, she knew, but that is not to be theirs. Their love is different. It has no past, and no future that can be thought about; it has only the present. Arthur says that in his mind she is his mystical wife. Jean agrees, but says that mystical wives do not wear physical rings.

Naturally, it is the Mam who solves the matter. She invites Jean to Ingleton, suggesting that Arthur come himself the following day. On the evening of Jean's arrival, the Mam has a sudden idea. She takes from the little finger of her left hand a small ring and slips it onto the same finger of Jean's hand. It is a pale cabochon sapphire which once belonged to the Mam's great-aunt.

Jean looks at it, twirls her hand, and promptly removes it. 'I cannot accept jewellery that belongs in your family.'

'My great-aunt gave it to me because she thought it went with my colouring. It did then; but no longer. It goes better with yours. And I think of you as part of the family. I have done so from the first day I met you.'

Jean cannot refuse the Mam; few can. When Arthur arrives, he is theatrically slow to notice the ring; finally, it is pointed out to him. Even then he disguises the pleasure he feels, commenting that it is not very large, and giving the women a chance to laugh at him. Now Jean wears not Arthur's ring but a Doyle ring, and that is just as good; perhaps better. He imagines seeing it against the cloth of a cluttered dining table and the keys of a piano, against the arm of a theatre stall and the reins of a horse. He thinks of it as a symbol of what binds her to him. His mystical wife.

Two white lies are allowed to a gentleman: in order to shield a woman, and to get into a fight when the fight is a rightful one. The white lies Arthur tells Touie are far more numerous than he ever imagined. At the beginning he assumed that somehow, in the bustle of his days and weeks, his ventures and enthusiasms, his sports and travels, the need to tell her lies would not arise. Jean would disappear into the interstices of his calendar. But since she cannot disappear from his heart, she equally cannot disappear from his mind and his conscience. So he finds that every meeting, every plan, every note and every letter sent, every thought of her, is hedged around with lies of one sort or another. Mostly they are lies of omission, though sometimes, necessarily, lies of commission; lies anyway, all of them. And Touie is so utterly trusting; she accepts, she has always accepted, Arthur's sudden changes of plan, his impulses, his decisions to stay or to go. Arthur knows she is without suspicion, and this scrapes at his nerves the more. He cannot imagine how adulterers can live with their consciences; how morally primitive they must be simply to sustain the necessary lying.

But beyond practical difficulty, ethical impasse and sexual frustration, there is something darker, something harder to face directly. The key moments in Arthur's life have always been shadowed by death, and this is another one. The sudden, wondrous love that has arrived can only be consummated and acknowledged to the world if Touie dies. She will die; he knows that, and so does Jean; consumption always claims its victims. But Arthur's determination to fight the Devil has resulted in a ceasefire. Touie's condition is stable; she no longer even needs the cleansing air of Davos. She lives contentedly at Hindhead, grateful for what she has, and exuding the gentle optimism of the consumptive. He cannot wish for her death; equally, he cannot wish for Jean's impossible position to continue without end. If he believed in one of the established religions, he would doubtless put everything in the hands of God; but he cannot do this. Touie must continue to receive the best medical attention and the strongest domestic support in order that Jean's suffering may continue as long as possible. If he takes any action, he is a brute. If he tells Touie, he is a brute. If he breaks off with Jean, he is a brute. If he makes her his mistress, he is a brute. If he does nothing, he is merely a passive, hypocritical brute vainly holding on to as much honour as he can.

Slowly, however, and discreetly, the relationship is acknowledged. Jean is introduced to Lottie. Arthur is introduced to Jean's parents, who give him a pearl and diamond pin-stud for Christmas. Jean is even introduced to Touie's mother, Mrs Hawkins, who accepts the relationship. Connie and Hornung are also apprised, though nowadays they are much taken up with marriage, their son Oscar Arthur, and life in Kensington West. Arthur gives assurances to everyone that Touie will be shielded at all cost from knowledge, pain and dishonour.

There are high-minded declarations, and there is daily reality. Despite family approval, Arthur and Jean are each liable to bouts of low spirits; Jean also becomes prone to migraines. Each feels guilt at having dragged the other into an impossible situation. Honour, like virtue, may be its own reward; but sometimes it does not feel enough. At least, the despair it provokes can be as sharp as any of the exaltation. Arthur prescribes for himself the collected works of Renan. Hard reading, with plenty of golf and cricket, will steady a man, keep him right in body and mind.

But these recourses can only do so much. You can thrash the other side's bowlers to all quarters, then pitch short into their batsmen's ribs; you can take a driver and punish a golf ball into the farthest distance. You cannot keep the thoughts at bay for ever; always the same thoughts, and the same repellent paradoxes. An active man doomed to inactivity; lovers forbidden to love; death which you fear and are ashamed to beckon.

Arthur's cricket season has been going well; scores made and wickets taken are relayed to the Mam with filial pride. She in return continues to give him the benefit of her opinions: about the Dreyfus Case, about the sacerdotal bullies and bigots in the Vatican, about the odious attitude towards France of that dismal paper the Daily Mail. One day, Arthur is playing at Lord's for the MCC. He invites Jean to watch him, and knows, when he comes out to bat, just where in 'A' Enclosure she will be sitting. It is one of those days when the bowlers have no secrets from him; his bat is impregnable, and scarcely registers the impact as he smacks and wheedles the ball around the field. Once or twice he lifts it straight into the crowd, and even has time to make sure beforehand that there is no danger of it dropping near her like a shell. He is jousting in the name of his lady; he should have asked for a favour to wear in his cap.

Between innings, he comes to seek her out. He needs no words of praise – he sees the pride in her eyes. She needs to walk a little after sitting on a slatted bench so long. They take a turn around the ground, behind the stands; beer wafts on the hot air. Amid an idling, anonymous throng they feel more alone together than under the friendliest chaperoning eye at a dinner table. They talk as if they had just met. Arthur says how he wishes he could have worn her favour in his cap. She slips her arm through his and they walk silently on, deep in happiness.

'Hello, there's Willie and Connie.'

It is indeed; coming towards them, also arm in arm. They must have left little Oscar with his nurse back in Kensington. Arthur now feels even prouder of his performance with the bat. Then he becomes aware of something. Willie and Connie are not slowing their pace, and Connie has started looking away, as if the back of the pavilion had become something of irreducible interest. Willie at least does not appear to be denying their existence; but as the couples pass, he raises an eyebrow at his brother-in-law, at Jean, and at their linked arms.