It seemed he was in some newly established place.

He had a sudden flash of suspicion! Surely this wasn't some hall of public exhibition! If it was he would give Warming a piece of his mind.

But it scarcely had that character.

And in a place of public exhibition he would not have discovered himself naked.
Then suddenly, quite abruptly, he realised what had happened.

There was no perceptible interval of suspicion, no dawn to his knowledge.