While reading my nightly Agatha Christie novel, I do run across words and ideas that are not familiar to me, being an American. Most Agatha Christie novels, being set in a different time and place, mention food and customs that I like to read more about.
Afternoon tea ( a late lunch) can be a sandwich and drink (hot tea, lemonade, beer). This is different than a high tea- which is more substantial- with sandwiches, scones, and cake. My daughter and mother in law like to visit a local tea room a couple times a year for a festive high tea.
I recently visited a local British shop and purchased fish paste and ham and chicken paste, which is a jarred sandwich filling. The unappetizing name of fish paste, etc is what Americans would call tuna, ham, or chicken SALAD. The taste was acceptable, but the texture was as smooth as paste!