He now realized the difficulties of his quest, and the absolutely wrong way in which he had set about it.

His imagination had run away with him.

It was no case for the imagination.
It was a case for patient investigation, close reasoning, logical deduction, all arts in which the imaginative man is almost inevitably deficient.
Langholm, however, had enough lightness of temperament to abandon an idea as readily as he formed one, and his late suspicion was already driven to the four winds.

He only hoped he had not shown what was in his mind at the club.

Langholm was a just man, and he honestly regretted the injustice that he had done, even in his own heart, and for ever so few hours, to a thoroughly innocent man.
And all up Piccadilly this man was sitting within a few inches of him, watching his face with a passionate envy, and plucking up courage to speak; he only did so at Hyde Park Corner, where an intervening passenger got down.
Langholm was sufficiently startled at the sound of his own name, breaking in upon the reflections indicated, but to find at his elbow the very face which was in his mind was to lose all power of immediate reply.
"My name is Severino," explained the other.