I've long loved the Beatles song "She's Leaving Home," but I've also long been puzzled by the line "waiting to keep the appointment she'd made, meeting a man from the motor trade." The Wikipedia page on the song has lots of information about how it was written, but it does not saying anything about the significance of "the motor trade." Does "the motor trade" have any significance here? (Perhaps, as an American, I am missing some British slang?)

Here's Brad Mehldau's version of the song, in any case: