It's not often the Queen shows up at a party unannounced, but when John and Frances Canning, two of her very ordinary subjects from Manchester, in Northern England, learned the monarch was going to be in town on the day of their wedding, they sent her an invitation on a whim. And, despite not sending an RSVP, she showed up.
Despite their shock, the groom had the presence of mind to bow, and the bride to curtsey as the monarch appeared and congratulated them, as this video of the event shows.
Elizabeth was in Manchester on Friday on official duties that included visits to Central Manchester University Hospitals and a new BBC complex.
She is making appearances around the country this spring as she celebrates her Diamond Jubilee, marking her 60 years on the throne.