GKC mentions in Agatha Christie novels

I know that GKC is mentioned in other places in her novels, but here are two of them that I remember off the top of my head. First, from Agatha Christie's The Murder at the Vicarage (1930)

"I hadn't really got down to the job, though," continued Lawrence, "because it occurred to me that I'd like to see Miss Marple, first, to make quite sure that no one did pass along the lane yesterday evening while we were in the studio."

I shook my head. "She was quite positive that nobody did."

"Yes, nobody whom she would call anybody- sounds mad, but you see what I mean. But there might have been someone like a postman or a milkman or a butcher's boy- someone whose presence would be so natural that you wouldn't think of mentioning it."

"You've been reading G.K. Chesterton," I said, and Lawrence did not deny it.

"But don't you think there's just possibly something in the idea?"

"Well, I suppose there might be," I admitted.

...and from her novel At Bertram's Hotel (1966)

"Now don't you worry, Mrs. McCrae," he said in his genial fashion, as he sat down to the meal she had prepared for his arrival. "We'll hunt the absent-minded fellow down. Ever heard that story about Chesterton? G.K. Chesterton, you know, the writer. Wired to his wife when he'd gone on a lecture tour 'Am at Crew Station. Where ought I to be?' "

[For more information about that anecdote, btw, see here.]