what two things were unusual about the check?

The cheque was picked up at four o'clock in the morning and believed to be a forgery. The hundred pounds came from another man's, and a very well known man's bank account.

"I took the liberty of pointing out to my gentleman that the whole business looked apocryphal, and that a man does not, in real life, walk into a cellar door at four in the morning and come out with another man’s cheque for close upon a hundred pounds."