A trace works by cross-checking a subject's known history — previous addresses, dates of birth, aliases, linked names and any documentation you already hold — against credit reference data, electoral and property records, company filings and open sources, then confirming the strongest match before it is reported. A result is only reported as confirmed when independent sources agree.
Tracing in the UK is not a database lookup. It is regulated personal-data processing, so a lawful basis is needed before enquiries begin, and the reason for the trace determines which data sources may lawfully be used.