Alistair and Doris' wedding

The Seventh Doctor did not originally go to the wedding of Alistair Gordon Lethbridge-Stewart and Doris, but later changed time to a minor extent so that he did attend after all.

Alistair and Doris only realised what had happened while looking through their wedding photographs one evening, and saw the Doctor had suddenly appeared in some of them — as well as beginning to vaguely recall seeing him at the wedding. (PROSE: A Romantic Evening)