A debtor is traced by working from identifiers rather than from the address on the file. Full name, date of birth, former addresses, telephone numbers and employment details are cross-matched against credit-header, electoral, property and mortality data, and the strongest match is corroborated against a second independent source before it is reported.
Where the result will be relied on in proceedings, the desktop stage is followed by a doorstep verification visit confirming occupation, and the whole enquiry is reported with the sources checked and the dates checked. That report is the evidence of the reasonable steps CPR 6.9(3) expects, and it is what supports an application under CPR 6.15 if no address can be established.