From the NSPCC.
"There are many important things to consider before you decide to leave a child alone. These include:
*the age of the child
*the child's level of maturity and understanding
*the place where the child will be left
*how long and how often the child will be left alone
*whether or not there are any other children with the child.
If you do leave a child alone, remember to:
*leave a contact telephone number and be available to answer it immediately
*talk to your child about keeping safe at home and point out the potential dangers
*tell them not to answer the door to strangers
*give clear instructions on what to do in an emergency - they should be able to phone the emergency services
*leave a list of trusted people they can contact
*put obvious dangers out of reach of children, for example, medicines, matches
*make sure that your child is happy about the arrangements and confident about being left
*tell your child when you'll be back and make sure you're back on time
*talk to him or her about it afterwards
"As a mum or dad, looking after your child is your number one priority." "There's no legally set age at which it's OK to leave your child at home alone. It depends on whether your child is mature enough to cope in an emergency and feels happy about being left." "Your children rely upon you to protect them and you are responsible for making sure they are happy, safe and well looked after in your absence"
And above all "Remember
* Never leave a baby or young child home alone, not even for a few minutes, regardless of whether they are
sleeping or awake. The most common place for accidents is at home and children under the age of five are the most injured group."