Tallulah that reminds me - we had been shopping at asda last year, when we got back to the car and were loading up the shopping I noticed in the next car a boy of around 6/7 and a 1yr old alone. I was apprehensive, but gave parents benefit of the doubt and thought that surely they couldn't be far away.
We were about to drive off when the older boy opened the car door and let the 1 yo get out! She was running around the bloody car with him chasing her and laughing. I got out and told him to get her back in, and asked where his mum was, he shot back into the car with her, and stuck his 2 fingers up at me 
I told him we weren't going anywhere until his mum got back and he suddenly looked worried.
15 minutes later mum and, I assume a friend, get back and I told her what had happened. She then proceeded to ball her head off at the boy for unlocking the car door, then turned to me and said, "she was asleep when we got here and I didn't want to disturb her" 
I just said, "you are responsible for the baby, NOT your ds, it's your fault she was running around in the road so I don't know why you're yelling at HIM. We got in the car and drove off to lots of vulgar swearing.
Vile woman.