I'm afraid I certainly can't identify it for sure, but bumping up kerbs puts mountings under severe stress.....
I can only recommend that the car is driven slowly and carefully to the nearest garage for a look see - so sorry I can't be more specific but maybe others will recognise the thing.
John
Is your girlfriend into classics, because it doesn't look like any mounting on the newer, BMW Mini One. It look a bit "light" for a mounting, don't you think?
FWIW, it's not a part I recognise from a real Mini. Like you say could already have been on the floor from the previous car that hit the curb like your missus did.