What are the 3 agencies that report credit scores?

In the UK, the 3 agencies are Callcredit, Equifax and Experian.

The USA has four: Experian, Equifax, TransUnion and Innovis.

You can usually find out from consumer websites which agency banks/card lenders use when they run a credit check, in order to get a copy of your report and check the details are OK.