When parents are employing a nanny or babysitter before the complete of the interview they will need to obtain a list of references and site other information about the candidate including identity check, Working With Children Checks, First Aid Certificate, and childcare qualifications (if the applicants said they had a qualification).  

Many parents find that it is often a good idea to enlist the service of a pre-employment screening company to undertake the necessary checks on their behalf including a National Police Check and Pre-Employment Screening Chec.

There are many companies out there providing these services for example The PRM Group or First Advantage are just two.