Whereabouts were his former haunts?
His rags, taken together with the low villain who seemed to know him and who even claimed to be his father, indicated that his home was in one or another of the poorest and meanest districts of London.

Would the search for him be difficult, or long?
No, it was likely to be easy and brief.

He would not hunt for the boy, he would hunt for a crowd; in the centre of a big crowd or a little one, sooner or later, he should find his poor little friend, sure; and the mangy mob would be entertaining itself with pestering and aggravating the boy, who would be proclaiming himself King, as usual.

Then Miles Hendon would cripple some of those people, and carry off his little ward, and comfort and cheer him with loving words, and the two would never be separated any more.
So Miles started on his quest.

Hour after hour he tramped through back alleys and squalid streets, seeking groups and crowds, and finding no end of them, but never any sign of the boy.