Morse arrested the doyenne of the family at the end, and the model train enthusiast's mother was released from gaol.

His insight came from remembering that upper class 'remain' was used in a phone call rather than middle class 'stay.'

Another episode hinged on spelling- a note was a forgery since only an illiterate (read non-Oxbridge) person would spell recognize with an 's.' Check your genuine Oxford English Dictionary- Englishmen educated at better schools spell the word with 'z' just like their American 'cousins.'

The series has quite a few of these little examples of class culture and speech. The interplay between Morse and Lewis is quite comedic if one is familiar with the peculiarities of the English classes and language.

The complete set of Morse episodes is available on DVD from Amazon, etc.