Margery Allingham 
The China Governess 

“It was called the wickedest street in London and the entrance was just here. I imagine the mouth of the road lay between this lamp standard and the second from the next down there.” In the cold darkness of the early spring night the Chief Detective Inspector of the area was talking like a guide book with sly, proprietorial satisfaction. He was a neat pink man whose name was Munday and he was more like a civil servant than a police officer. His companion, who had just followed him out of the black chauffeur-driven police car drawn up against the curb, straightened himself and stood looking at the shadowy scene before him without speaking.