how do you persuade people to take the pictures?
Find a flat surface on which to rest the camera, and set the timer!

But wait, where's the pic of St. Paul's? Isn't that another must-see sight?!
One to do next time I'm in London. I was thinking of you yesterday when I was in London yesterday, KCW, wasn't that a Freedom Kilt you were wearing in some of your London pics?