The police can check if someone involved with a child has a record of sexual offences.
You do not have to be a relative of the child you are concerned about.
You have to visit your local police station to ask them to check someone’s background.
At the police station, you will need to:
show some ID, eg your passport or driving licence
say why you want to have this particular person checked
tell the police what your relationship to the child is
Call 999 if you think the child is in immediate danger.
For further information on Getting a Police to check on someone involved with a child can be found on GOV.UK's website.