Well, that was the date!
The changing of the guards at Buckingham Palace on July 4th, 2005. I've now seen the changing of the guards twice, and probably don't need to see it again, but if you've never seen it, it's worth braving the crowds just once. No doubt, if I go to London with someone who hasn't been there before, I'll do it again, though.
Just to be thorough, this photo was a jpeg from a cheap camera with a plastic lens . . . and all the attendant problems of in-camera sharpening, etc. processing was done mainly in LightroomCC, but there was a bit of Photoshop, as I recall.