Shall we walk on a little ?" "Very well," she agreed, paying no attention to him.
Aware of her preoccupation, or absorbed in his own thoughts, Ralph said nothing further; and in silence they walked some distance along the Strand.

Ralph was doing his best to put his thoughts into such order that one came before the rest, and the determination that when he spoke he should speak worthily, made him put off the moment of speaking till he had found the exact words and even the place that best suited him.
The Strand was too busy.

There was too much risk, also, of finding an empty cab.

Without a word of explanation he turned to the left, down one of the side streets leading to the river.

On no account must they part until something of the very greatest importance had happened.