In the novel A Caribbean Mystery, Major Palgrave was an old major, who used to bore others with his endless stories.
He once told a story to Miss Marple about a murderer.
In the 1983 Warner Bros adaptation, Major Palgrave is portrayed by Maurice Evans. Here he has the first name "Geoffrey". In this adaptation that fact that he has a glass eye is not a plot element and it is not stated whether he has a glass eye or not.
In the BBC 1989 adaptation, Major Palgrave is portrayed by Frank Middlemass. Here he has the initials "C. J." The poison used on him here is called "tetrauwolfide", also used for high blood pressure. Here also, Palgrave had a different career path. Besides a military career, which accounted for most of his stories and photos, he later became a colonial policeman and was seconded to the St Kitts and Nevis police between 1947 and 1950 and this is how he got the photo of the person he claimed was a murderer. He boasted to Miss Marple that he is not on Barbados just for a holiday.
In the 2013 ITV adaptation, Major Palgrave is played by Oliver Ford Davies. His first name is Robert and he has a D.S.O. The murderer whose photo he wanted to show Miss Marple had been obtained in Kenya during his army days. It was a picture of a man holding a marlin. Like in the original, the glass eye is a significant plot element.