At what age would you allow your child to use a public loo alone?

When a US mum found herself in a predicament because of this sign on a bathroom door, she snapped a picture on her phone. The photo of the sign, which says 'Please, boys over 6 years of age use Men's restroom' has since gone viral, sparking a debate about the safety of allowing a child to enter a public bathroom alone. Mums took to Twitter to voice their opinions on the sign, with many pointing out that each child is different and their safety should be dictated by their parents alone:                 Six-years-old seems a little too young to us, but what is an acceptable age for a child to use a public bathroom on their own? One thing is for sure, a sign like this wouldn't stop us from doing what's safe over what's demanded by a hastily printed piece of paper.