With a resolution to probe this mystery slowly, and without unseemly haste, I dropped the subject, and commenced to ask his advice regarding the complicated case of Lady Twickenham. The history of it, and the directions he gave can serve no purpose if written here; therefore suffice it to say that I remained to dinner and caught the nine o’clock express back to London.

While at dinner, a meal served in that severe style which characterised the austere old man’s daily life, I commenced to talk of the antics of insane persons and their extraordinary antipathies, but quickly discerned that he had neither intention nor desire to speak of them. He replied in those snappy monosyllables which told me plainly that the subject was distasteful to him, and when I bade him good-bye and drove to the station I was more puzzled than ever by his strange behaviour. He was eccentric, it was true; but I knew all his little odd ways, the eccentricity of genius, and could plainly see that his recent indisposition, which had prevented him from attending at Harley Street, was due to nerves rather than to a chill.

The trains from Brighton to London on Sunday evenings are always crowded, mainly by business people compelled to return to town in readiness for the toil of the coming week. Week-end trippers and day excursionists fill the compartments to overflowing, whether it be chilly spring or blazing summer, for Brighton is ever popular with the jaded Londoner who is enabled to “run down” without fatigue, and get a cheap health-giving sea-breeze for a few hours after the busy turmoil of the Metropolis.

On this Sunday night it was no exception. The first-class compartment was crowded, mostly be it said, by third-class passengers who had “tipped” the guard, and when we had started I noticed in the far corner opposite me a pale-faced young girl of about twenty or so, plainly dressed in shabby black. She was evidently a third-class passenger, and the guard, taking compassion upon her fragile form in the mad rush for seats, had put her into our carriage. She was not good-looking, indeed rather plain; her countenance wearing a sad, pre-occupied expression as she leaned her chin upon her hand and gazed out upon the lights of the town we were leaving.

I noticed that her chest rose and fell in a long-drawn sigh, and that she wore black cotton gloves, one finger of which was worn through. Yes, she was the picture of poor respectability.

The other passengers, two of whom were probably City clerks with their loves, regarded her with some surprise that she should be a first-class passenger, and there seemed an inclination on the part of the loudly-dressed females to regard her with contempt.

Presently, when we had left the sea and were speeding through the open country, she turned her sad face from the window and examined her fellow passengers one after the other until, of a sudden, her eyes met mine. In an instant she dropped them modestly and busied herself in the pages of the sixpenny reprint of a popular novel which she carried with her.

In that moment, however, I somehow entertained a belief that we had met before. Under what circumstances, or where, I could not recollect. The wistfulness of that white face, the slight hollowness of the cheeks, the unnaturally dark eyes, all seemed familiar to me; yet although for half an hour I strove to bring back to my mind where I had seen her, it was to no purpose. In all probability I had attended her at Guy’s. A doctor in a big London hospital sees so many faces that to recollect all is utterly impossible. Many a time I have been accosted and thanked by people whom I have had no recollection of ever having seen in my life. Men do not realise that they look very different when lying in bed with a fortnight’s growth of beard to when shaven and spruce, as is their ordinary habit: while women, when smartly dressed with fashionable hats and flimsy veils, are very different to when, in illness, they lie with hair unbound, faces pinched and eyes sunken, which is the only recollection their doctor has of them. The duchess and the servant girl present very similar figures when lying on a sick bed in a critical condition.

There was an element of romantic mystery in that fragile little figure huddled up in the far corner of the carriage. Once or twice, when she believed my gaze to be averted, she raised her eyes furtively as though to reassure herself of my identity, and in her restless manner I discerned a desire to speak with me. It was very probable that she was some poor girl of the lady’s maid or governess class to whom I had shown attention during an illness. We have so many in the female wards at Guy’s.

But during that journey a further and much more important matter recurred to me, eclipsing all thought of the sad-faced girl opposite. I recollected those words I had overheard, and felt convinced that the speaker had been none other than Ethelwynn herself.