You are probably right about the crossword clue. But the grandmother's envy was not pretend, but perhaps colored by surprise. I think the surrey with fringe was

You are probably right about the crossword clue. But the grandmother's envy was not pretend, but perhaps colored by surprise. I think the surrey with fringe was a luxurious status symbol, like having a Mercedes-Benz or something. The surprise would be like finding out that your plain Jane unassuming friend grew up in a fairly rich family.