I have decided that the club sandwich of my youth was considered elegant because not only was it triple-deckered (oh my); not only did it have toothpicks with colored cellophane curlies; not only did it's very name conjure up wealth; it was cut on the diagonal twice. We cut at right angles in our clan. People who cut on the diagonal were considered a little, well, showy. Restaurants might do that, trying to impress you, but Scandinavians actively backed away from such display for everyday use. If you went to a friend's house and his mother cut the sandwich on the diagonal, you didn't mention it, but you thought that perhaps they were getting a bit above themselves.
Your grandmother might cut the sandwiches for guests on the diagonal for an Occasion of some sort but for everyday - we weren't that sort of people. Relatives who had moved away might risk it - living in more glamorous places they rather had to - but we didn't.
Even as late as my college days, waiting on tables, I noticed that it was older women of the better sort who ordered the club sandwich