Well, I know my daughter has been alone for periods of a few minutes when she was little. Thank goodness Bill Spedding was not around.
However, she did manage to take the poop out of her nappy one day when she was a toddler, and I was quickly grabbing a few bits, and smear it all over the walls. (Boy, do I remember that!)
I would venture to say that there is not one parent out there, who has not left their child alone for a couple of minutes. Not in the bathtub, not near the pool, not in a dangerous place. But alone, nevertheless, while they quickly went to grab something.
William was not even left alone. Grandma was there. She just couldn't follow him because she was recovering from illness, and expected him to run back in a minute. He knew his boundaries.