I am often asked to authenticate police checks for use overseas. In the United Kingdom these can be obtained from the ACRO Criminal Records Office, from Disclosure Scotland and the Disclosure & Barring Service (DBS). Generally, for the purposes of authenticating and attesting such documents, the ACRO police certificates are easier to work with and you can ask for them to be signed in “wet ink”. In contrast the Disclosure Scotland documents are not signed and therefore more difficult to process.
See: www.acro.police.uk/Police-Certificates