In the last photo where Princess Margaret is exiting her car and wearing a maple leaf brooch -- I don't think that it is the one which was auctioned by Christie's.
For the brooch auctioned see https://www.christies.com/lot/lot--4718052/?from=salesummary&intObjectID=4718052&lid=1&ldp_breadcrumb=back
Below is a comparison of the two items.
On the other hand, if the date of the last photo is accurate then the maple leaf brooch Princess Margaret was wearing makes sense of a report in the Daily Telegraph 6 August 1958 which stated that the maple leaf brooch had diamonds forming a fleur de lys.
I think we have a mystery to solve.