Clients paid the private detectives to intercept phone calls and e-mails

Ex-Met officers Jeremy Young and Scott Gelsthorpe even tried to hack into the New York Stock Exchange. They received 27 months and two years respectively.

Three former Staffordshire officers were jailed for unlawfully accessing the police national computer.

John Matthews was jailed for 14 months, Anthony Wood received 10 months, and Gary Flanagan got a three-month term.

Matthews, 59, from Stafford, used his position as a serving detective sergeant to run unauthorised checks on vehicles and individuals using the police national computer (PNC).

He passed the data to his former police colleagues Flanagan, 43, and 63-year-old Wood, who ran private detective agency Brian Harrison Investigations in Stoke-on-Trent.

Flanagan, of Newcastle-under-Lyme, was a former detective constable who resigned in 1989, and Wood, also from Stafford, was an ex-detective sergeant with more than 30 years' experience.

POLICE CONNECTIONS Jeremy Young, 43 - ex-Met Police constable Scott Gelsthorpe, 32 - ex-Met Police officer John Matthews, 59 - ex-Staffs detective sergeant Gary Flanagan, 43 - ex-Staffs detective constable Anthony Wood, 64 - ex-Staffs detective sergeant

At Southwark Crown Court, judge Paul Dogson said: "One of the distressing aspects of this case is that the good work that is done by the vast majority of the police officers in this country is damaged, I hope not severely but certainly damaged, by the misconduct of those of you acting police officers who abuse the system and those retired officers who go along with it."

It was "that abuse of trust that so many could do but so few take", that made him consider the offences so seriously, the judge added.

Another man, Gordon Bucher, 53, from Hereford, was jailed for two months for aiding and abetting misconduct in a public office.

He ran another detective agency Phoenix Investigations and also unlawfully gained access to material from the PNC.

A seventh man David Carroll, 59, from Highgate, north London, had his sentencing adjourned due to ill health.

He was earlier convicted of playing a role in the running of Young and Gelsthorpe's company Active Investigation Services (AIS).

All of the men were convicted as part of Operation Barbatus, carried out by the Met Police's anti-corruption team.

Share prices

Gelsthorpe, 32, of Kettering, Northants, and Young, 40, of Ilford, east London, ran AIS - dubbed "Hackers Are Us" - for five years from 1999 - at a time when Young was still a serving police constable with the Metropolitan Police.

For much of that time, he was on sick leave from his job.

It's clear these dishonest private investigators have a pool of illegal services they can call upon when they need them

Det Insp Kevin Hyland

AIS was paid substantial sums to investigate cheating spouses and business rivals. Some of the work they did themselves and other aspects were contracted out.

One such "contractor" was a computer hacker based in Arizona, Marc Caron, who used viruses to gain access to people's e-mail accounts.

One of Caron's victims was Tamara Mellon, millionaire creator of the Jimmy Choo shoe empire.

But Caron and AIS set their sights even higher. They tried to hack into computers at the New York Stock Exchange, hoping to get share prices 20 minutes before they were released.

Police still have not discovered who was paying them to attempt it.

Another high-profile client was waste disposal firm Atlantic Waste. Boss Adrian Kirby paid AIS to snoop on staff at the Environment Agency investigating the company's dumping tactics.

Miranda Moore QC said this was "the most serious and the most sustained attack" carried out by AIS.

Disabled permits

Police say AIS may have made millions from their illegal activities, but exactly how much is still being investigated.

They showed flashes of living luxuriously - Young, for example, had a birthday party for a dozen people at the Park Lane Hilton and Carroll drove a £100,000 Bentley.

Yet at the same time, rather than pay for parking at their expensive City of London offices, they all had forged disabled permits.

Det Insp Kevin Hyland, who led Operation Barbatus, said he was sure there were other private detectives doing the same thing.

"It's clear these dishonest private investigators have a pool of illegal services they can call upon when they need them," he added.