As others have stated, you accessed a US website, so it's not unreasonable that you could only obtain US data.
As Ethel points out, it's strictly illegal (under data protection laws) for anyone to access UK criminal records. Obviously, certain official bodies (such as the police) are exempt but even they need to have 'justifiable cause' to access criminal records. All searches of criminal records, by police officers, are recorded and subject to audit. There was a well-reported case where a long-serving police officer used the system to check whether his daughter's boyfriend had a criminal record. His unauthorised search was picked up and he was sacked, prosecuted and imprisoned. There's no way you can legally access UK criminal records.
Chris