John and Frances Canning were just an ordinary bride and groom in Manchester; hearing that the Queen was going to be in the city on other business the day of the wedding, they invited her as a sort of lark.
She and Prince Philip showed up. One suspects that it was also a bit of a treat for the Queen; she has to go around on a lot of official business, especially since this is her Diamond Jubilee year, and most of it probably not as fun as just showing up, even briefly, to make a a newlywed couple's wedding day even better.
