Journalists commissioned a private detective to find out personal details about sportsmen and celebrities including Hugh Grant and his former girlfriend Liz Hurley, the Leveson Inquiry has heard.
Records seized from investigator Steve Whittamore in 2003 contained a "veritable treasure trove" of information about how newspapers ordered searches on everything from addresses to criminal records, the hearing was told.
The paperwork includes references to investigations into members of a UK national sports team and a "B&B sex party".
Whittamore was asked to do an address search for Grant and Hurley in south London and a vehicle registration mark (VRM) check relating to the Love Actually star, the press standards inquiry heard.
Alec Owens, senior investigating officer for the Information Commissioner's Office (ICO) from 1999 until 2005, recalled: "We went to see Mr Grant at his offices because a VRM comes up against his name. As it turned out he couldn't recall this and possibly thought he may have been in a friend's car or talking to somebody standing by that car."
One newspaper paid £800 in 2002 for the June 2001 phone bill of an unnamed sports star from a national side, the inquiry was told.
Whittamore's Hampshire home was raided in March 2003 as part of a major ICO investigation into the illegal purchase of confidential information called Operation Motorman.
The private detective was convicted in 2005 of illegally accessing data and passing it to journalists.
Robert Jay QC, counsel for the inquiry, said there was a "veritable treasure trove" of information in Whittamore's files.
Inquiry chairman Lord Justice Leveson added: "Mr Whittamore had collected together a vast amount of personal data. The documents identify the names of titles, specify journalists at the titles apparently or inferentially making the requests."