It was my understanding they found two sets of young boys' bones under a closed-off stairwell during renovations of the tower. Supposedly the ages of the individuals when they died matched the ages of the princes in the tower. One of those wonderful mysteries that just go on and on.
Have you been to the Tower of London? We were there about 15 years ago and in the courtyard area there was a small patch of ground fenced off with a sign that said the little princes had been beheaded there. We took a picture of the patch of grass and when it was developed there were what looked like 2 misty figures there, one a little taller than the other. In another frame the area with full of what appeared to be cigarette smoke, but there were no other people near and no one was smoking anywhere in the area. Weird?