What precautions do you take to make sure an individual cannot be identified from their postcode?
There are general precautions about the security of our servers which I am sure every good business would adopt, but we make a special effort with postcodes.
I don't know if your child competed the survey online or on paper - the account to be given in each case is slightly different.
Online, the postcodes are encrypted using GnuPG when storing, and downloaded with the encryption intact (screenshot).