This 1960s 'found' snapshot looks like the changing of the guard (or similar parade), probably at Windsor Castle (I still haven't managed to get round all these castles ;)). But look to the left of the image, the lady with the handbag, who appears to have just alighted from that rather smart car, and who has obviously caught the eye of the policeman, could that be HM the Queen or the Queen Mother?
Here we are undecided . . . I think it might be as this is just the kind of snapshot a visitor would be likely to take, with the car, the attention of the policeman all adding weight to that conclusion. However another opinion says the Queen doesn't wear such flat shoes. So then we arrived at the question, are those the Queen's legs?