From government website
Leaving children at home alone
There is no legal age limit for leaving a child on their own, but it is an offence to leave a child alone if it places them at risk. Parents can be prosecuted for neglect if they leave a child unsupervised ?in a manner likely to cause unnecessary suffering or injury to health? (Children and Young Person?s Act).
How mature is the child?
The most important factor to consider is how mature the child is. For instance, it may be okay to leave a very mature or ?grown up? 12 year old alone for a day while you are at work, but not a 13 year old who is not mature.
The National Society for the Prevention of Cruelty to Children (NSPCC) advises that:
children under the age of thirteen are rarely mature enough to be left alone for a long period of time
children under the age of sixteen should not be left alone overnight
babies, toddlers and very young children should never be left alone
Things to remember
If you do leave your child home alone, remember to do the following:
leave a contact phone number and make sure you can answer it right away
leave a separate contact list of people you trust, in case they can?t get hold of you
talk to your child before you leave about how to stay safe, and tell them not to answer the door to strangers
make sure dangerous objects like matches and knives are out of reach, as well as medicines and dangerous chemicals
leave clear instructions on what to do in case of an emergency (like a fire)
tell them what time you will be back, and don?t be late
set some basic rules about what they can and can?t do while you are out
teach them basic first aid