As someone who reads a lot of old true crime, I don't think it was at all unusual, at least not in Great Britain. As long as the convict seemed sane and the crime wasn't particularly horrible (such as child murder), the jailers were used to criminals and could get along well with them. I've read accounts of Dr. Crippen (very famous cause celebre in 1910, convicted of killing his wife), and his jailers were apparently quite fond of him. Same with the Frederick Bywaters-Edith Thompson murder of 1922 (they were convicted of killing Mrs Thompson's husband). The jailers were particularly friendly with Bywaters.
