A Devon and Cornwall Police inquiry which unearthed evidence that a serving officer carried out illegal data checks on former Prime Minister Gordon Brown should be part of the public inquiry into phone hacking, a Westcountry MP has said.

Operation Reproof exposed a web of alleged leaked information, fed from a Devon and Cornwall police officer, among others, to a network of private investigators.

A complex, two-year investigation took detectives all over the country and resulted in six men – two serving police officers, two former officers and two private investigators – being charged in 2004.

But the case collapsed after nearly two years in the courts, with Judge Paul Darlow commenting it was "not a proportionate use of valuable resources to prosecute these matters".

Attention has turned back to the inquiry amid continuing revelations about phone-hacking. One former detective told the Western Morning News that for four years between 2002 and 2006 "Devon and Cornwall Police were right at the heart of what we now know was going on at the News of the World".

Now, South West Devon MP Gary Streeter has called for the evidence to be examined as part of the public inquiry ordered by Prime Minister David Cameron into media practices and relations between the Press, politicians and police.

"The information should be put in front of Lord Justice Leveson," the Conservative MP said. "It is an important case in terms of its scale and depth – this is not just about the Metropolitan Police."

Mr Streeter said he believed the decision not to proceed with the case was "poor" and needed further explanation.

"We need to get to the bottom of this case," he added. "If it had been pursued we could have resolved these things very quickly."

Reports have suggested the Metropolitan Police has already called for files from an investigation carried out by the Information Commissioner's Office (ICO) in 2003.

The ICO's inquiry, Operation Motorman, was sparked by the Devon and Cornwall Police probe.

A 2006 report by the ICO explained: "While the ICO had long suspected the existence of an organised trade in confidential personal information, charting the full extent of any unlawful activity is naturally fraught with difficulty.

"An insight into the scale of this unlawful market came in late November 2002 when the ICO was invited to attend a search of premises in Surrey executed under warrant by the Devon and Cornwall Constabulary.

"The raid concerned the suspected misuse of data from the Police National Computer (PNC) by serving and former police officers."

In all, Devon and Cornwall detectives investigated 37 people, with the final evidential file focused on 100 alleged breaches of data related to 93 individual "victims", including then chancellor Gordon Brown and Labour MPs Martin Salter and Nick Brown.

It was alleged that former Exeter-based Detective Constable Philip Diss, who died in May, carried out two of the PNC checks in September 2000. Two months later he carried out a check using the then chancellor's full name – James Gordon Brown – and his date of birth. Each search ended with "no trace".

The police investigation resulted in charges against six defendants, all linked to the leaking of confidential information.

Mr Diss, from Exeter, was accused of misconduct in public office by disclosing data to Alan Stidwill. CID officer Robert Cornish, of Budleigh Salterton, East Devon, faced the same charge.

Peter Hill, from Sidmouth, a retired detective who had become East Devon District Council's investigations officer, was charged with disclosing information from the Department for Work and Pensions system to Mr Stidwill.

Mr Stidwill, who retired from Devon and Cornwall Police in 1994 and established SAS Investigations in Exmouth, was accused of procuring Mr Diss, Mr Cornish, and Mr Hill to commit misconduct.

Andre Laloi, of Horley, Surrey, who was alleged to have procured Mr Diss to commit misconduct, faced five charges.

Christopher Dewse, of Crawley, Sussex, was charged with four counts of obtaining information and one count of procuring Mr Diss to commit misconduct.

All charges against all of the six defendants were dropped before it went to trial.