The Media Column: 'The day the police showed me snaps of the prostitute and the pineapples'

Mark Daly, the BBC undercover journalist, has triggered a nationwide inquiry into police racism with his exposé of the recruitment process at Greater Manchester police. Daly's rewards for bringing the scandal to public attention through the documentary The Secret Policeman have been an attack on his integrity by the Home Secretary and a criminal investigation that means he remains on police bail.

This remarkable case has thrown light not just on bigotry among those paid to protect the public, but on the delicate relations between journalists and police officers. Investigative journalism sometimes strays into grey areas where reporters find themselves treading a thin line between exposing criminal activity and encouraging it. While journalists invariably see themselves as acting "in the public interest" and feel that they should be immune to prosecution, police officers often regard their activities with suspicion. Newspaper "dossiers" are received with little enthusiasm in CID offices, because the "evidence" that they contain is often inadequate to put before a court - and because journalists who uncover crime are exposing police shortcomings.

Like Daly, I once found myself under investigation, after I wrote a story on crack use in Birmingham for a regional newspaper in the 1980s. Somewhat naively, I followed the tabloid convention of obtaining a tiny quantity of the drug and handing it over to be "destroyed" by the police. Minutes later, I was in the headquarters of West Midlands police, being subjected to a classic "good cop, bad cop" interrogation and being warned that I was looking at a seven stretch.

With hindsight, I feel lucky that no one in a Pink Panther suit jumped out of a cupboard to rough me up (a favoured technique of the time, based on the premise that no jury in the land would believe such an outrageous tale). My grilling seemed all the more unreasonable given that a member of the force had visited the paper only days earlier and "planted" a lump of cannabis in the newsroom as a prank. A member of the business desk took that tiny consignment home to "destroy" it.

As an investigative journalist, you are not always certain where you stand with the police. Before I was hauled in, I was so pally with the drugs squad that they had even shown me their private collection of Polaroids taken on police raids, including one of a naked prostitute adorned with cherries, pineapple rings and a banana. She had been "fruit cocktailed", they informed me.

Officers may reasonably argue that they are never quite sure where they stand with journalists, given that sharing information could - and has - cost them their jobs. Years ago, it was common for junior officers to go drinking with reporters. I recall one police contact who liked a pint. Unlike the officers in Daly's film, he tried to be culturally aware and had taken an interest in Caribbean patois. Unfortunately, he had taken to the extreme the concept that words such as "bad", "wicked" and "rough" all translated as the opposite. "So if someone tells you they haven't got a bucky [slang for gun], it actually means they have," he told me with frightening sincerity.

Such meetings are now rare, as interaction with journalists becomes the preserve of media-literate senior officers. Which is why Daly's account of life among the trainees was so insightful and so important.

* The BBC has been less informative in explaining to us why it deserves £2.7bn of taxpayers' money each year. While the BSkyB chief Tony Ball and the Tory Culture spokesman John Whittingdale shape the debate on the meaning of public-service broadcasting and the renewal of the BBC's charter in 2006, nothing but silence comes from the corporation. "Frankly, I'm amazed," one senior public servant told me. "In the past, the BBC has been out there setting the agenda."

So, to White City, to speak to the man who masterminded the former director general John Birt's charter-renewal campaign in 1996. Matthew Bannister, the BBC's erstwhile director of radio, is enjoying a new lease of life as a talk-show presenter on Radio 5 Live. A decade ago, his title was "project co-ordinator, charter renewal". He helped to set up 25 internal workshops to debate the issues and produced a powerful document called "Extending Choice". Published four years before the charter came up for renewal, it enabled Birt to set the parameters for the ensuing debate. According to Bannister, "Because we had had that debate, we were well prepared to make the argument."

Asked about the current silence from the BBC, Bannister says: "I think it's very important that the BBC should articulate a clear vision of what it thinks public-service broadcasting means in 2003 and beyond." He is careful not to criticise Greg Dyke, the man who pipped him to become director general in 1999, but thinks the BBC should make its case. "It would be helpful to hear some leadership from the BBC," he says. "I suspect the leadership has been a bit distracted this summer."