The next time he and Jean meet, he takes charge. He must do so: he is the man, he is older; she is a young woman, possibly impetuous, whose reputation must not be tarnished. At first she appears anxious, as if he is going to dismiss her; but when it becomes clear that he is merely organizing the terms of their relationship, she relaxes, and at times appears almost not to be listening. She becomes anxious again when he is stressing how careful they must be.

'But we are allowed to kiss one another?' she asks, as if verifying the terms of a contract she has signed while happily blindfolded.

Her tone makes his heart melt and his brain blur. As confirmation of the contract they kiss. She likes to peck at him rather, with eyes open, in birdlike attacks; he prefers the long adhesion of the lips, with eyes closed. He cannot believe he is kissing someone again, let alone her. He tries to stop himself thinking in what ways it is different from kissing Touie. After a while, however, the perturbance starts up again, and he pulls back.

They are to meet; they are to be alone together for limited periods; they are allowed to kiss; they are not to become carried away. Their situation is intensely dangerous. But again she appears to be only half-listening.

'It is time I left home,' she says. 'I can share a flat with other women. Then you may come and see me freely.'

She is so different from Touie: direct, frank, open-minded. She has treated him from the start as an equal. And she is an equal in terms of their love, of course. But he has the responsibility for them, and for her. He must see that her straightforwardness does not lead her into dishonour.

There are times, in the following weeks, when he even begins to wonder if she was not expecting him to make her his mistress. The eagerness of her kisses, the disappointment at his drawing back; the way she presses herself against him, the sense he sometimes has that she knows precisely what is going through him. And yet he cannot think this. She is not that sort of woman; her lack of false modesty is a sign that she trusts him entirely, and would trust him even if he were not the man of principle that he is.

But it is not enough to solve the practical difficulties of their relationship; he also needs moral approval. Arthur takes the Leeds train from St Pancras in a state of trepidation. The Mam remains his final arbiter. She reads every word he writes before it is published; and she has done the equivalent for his emotional life. Only the Mam can confirm that the course of action he proposes is correct.

At Leeds he takes the Carnforth train, changing at Clapham for Ingleton. She is waiting at the station in her wickerwork pony-and-dog cart; she wears a red coat and the white cotton cap she has taken to affecting in recent years. The two ambling miles in the cart seem interminable to Arthur. The Mam defers constantly to her pony, which is called Mooi, and has its eccentricities, such as a refusal to go past steam engines. This means that roadworks have to be avoided, and each whim of equine inattention flattered. At last, they are inside Masongill Cottage. Arthur immediately tells the Mam everything. Everything, at least, that counts. Everything necessary for her to give him advice on this high and heaven-sent love of his. Everything about the sudden wonder and sudden impossibility of his life. Everything about his feelings, his sense of honour and his sense of guilt. Everything about Jean, her sweetly direct nature, her incisive intelligence, her virtue. Everything. Almost everything.

He backtracks; he starts again; he goes into different detail. He stresses Jean's ancestry, her Scottishness, a lineage designed to seduce any amateur genealogist. Her descent from Malise de Leggy in the thirteenth century, and by another line from Rob Roy himself. Her present condition, living with wealthy parents in Blackheath. The Leckie family, respectable and religious, who made their money in tea. Her age, twenty-one. Her fine mezzo voice, trained in Dresden and soon to be perfected in Florence. Her supreme ability as a horsewoman, which he has yet to witness. Her quickness of sympathy, her sincerity and strength of character. And then her personal appearance, which sends Arthur into rapturous mode. Her slender frame, small hands and feet, dark gold hair, hazel-green eyes, gently elongated face, delicate white complexion.

'You paint a photograph, Arthur.'

'I wish I had one. I asked her, but she says she takes a poor picture. She is reluctant to smile for the camera, because she is self-conscious about her teeth. She told me quite straightforwardly. She considers them oversized. Of course they are nothing of the sort. She is such an angel.'

The Mam, listening to her son's account, does not fail to observe the strange parallel that life has thrown up. For years she was married to a man whom society politely chose to regard as an invalid, whether he was being brought home by cadging cabmen or locked away under the disguise of an epileptic. In his absence and incapacity, she had found comfort in the presence of Bryan Waller. Back then, her sulky, aggressive son had dared to criticize; at times, by silence, almost to impugn her honour. And now her favourite, her most adored child, has in turn discovered that the complications of life do not end at the altar; some might say that this is where they begin.

The Mam listens; she understands; and she condones. What Arthur has done is correct, and consistent with honour. And she would like to know Miss Leckie.

They meet; and the Mam approves, as she approved of Touie back in Southsea days. This is not an unthinking endorsement of an indulged son. In the Mam's view, Touie, pliant and agreeable, was exactly the right wife for an ambitious yet confused young doctor needing acceptance in the kind of society that would provide him with patients. But were Arthur to marry now, he would need someone like Jean, someone with capabilities of her own, and with a clear, forthright nature which at times reminds the Mam a little of herself. Privately, she notes that this is the first intimate woman friend to whom her son has not given a nickname.

A Gower-Bell loudspeaking telephone, shaped like a candlestick, stands on the hall table at Undershaw. It has its own number – Hindhead 237 – and, thanks to Arthur's name and reputation, it does not, as many others do, share a party line with a neighbouring house. Even so, Arthur never uses it to telephone Jean. He cannot imagine working out when Undershaw will be empty of servants, the children at school, Touie resting and Wood off on his walk, and then standing in the hall with lowered voice and his back to the stairs: standing beneath the stained-glass names and shields of his ancestors. He cannot picture himself doing that; it would be proof of intrigue, not so much to anyone who might see him in that posture, but to himself. The telephone is the chosen instrument of the adulterer.

So he communicates by letter, by note, by telegram; he communicates by word and by gift. After a few months Jean is moved to explain that the flat she occupies has only a certain amount of space, and though she shares it with trusted friends, the ring of the delivery boy has become embarrassing. Women who receive large numbers of presents from gentlemen – or, more compromisingly, from one particular gentleman – are assumed to be mistresses; at the very least, potential mistresses. When she points this out, Arthur rebukes himself for a fool.

'Besides,' says Jean, 'I do not need assurances. I am certain of your love.'

On the first anniversary of their meeting, he gives her a single snowdrop. She tells him that this brings her more pleasure than any amount of jewellery or dresses or potted plants or expensive chocolates, or whatever it is that men give to women. She has few material needs, and these are easily met by her allowance. Indeed, the fact of not receiving presents is a way of marking that their relationship is different from the humdrum arrangements of others in the world.