Alan Carslake

In the short story In a Glass Darkly, Alan Carslake is the younger brother of Neil. He is one year younger than Neil and two years older than their sister Sylvia.

When Sylvia decides to leave her husband, she tells him in a letter that she is going to the one person who loves and needs her. Her husband assumes that this refers to another lover, but it is revealed that Sylvia was actually referring to Alan.

Portrayals
In the episode The Case of the Middle-aged Wife of The Agatha Christie Hour, an TV film adaptation of the story, the part of Alan is played by Jonathon Morris. No description was given about Alan in the original story. In the adaptation, Alan is portrayed as a poet and a free spirit. After Sylvia had married Matthew Armitage, Alan visited them at their farm in Suffolk. He chided Matthew for keeping Sylvia cooped up at the farm. He should let her out to enjoy herself in London, after all, "infidelity is in the air". The intensely jealous Matthew disagreed. "Not in Suffolk," he retorted. Later in the story, Sylvia leaves Armitage goes back to her family home at Badgeworthy to look after Alan because he had been depressed.