A few years ago, the Inland Revenue decreed that to save them the trouble, we would all have to do our own tax assessments from now on.

Make someone else do the donkey work: that was the thinking - and to no-one's great surprise, the idea soon spread.

Television was next to take it up. Having apparently run out of genuine celebrities, producers turned to us to supply a fresh batch. Schedules became stuffed with slices of "real life", and soon we had made stars of incompetent learner drivers, harassed airport stewards and nervous cruise ship singers.

But next week, docu-soap, as the genre has become known, moves into controversial new territory, with the welcoming on to the celebrity roster of a bunch of convicted criminals.

A major documentary serial, shot in Yorkshire and screened twice a week on BBC1, will introduce us to the inmates and staff of a women's prison, and invite us to be their friends.

Those featured include drug addicts, thieves, burglars and fraudsters. It's a long way from Sunday Night at the Palladium.

"I thought long and hard about this," says Christopher Terrill, the producer who brought us The Cruise and whose name is now on the end credits of Jailbirds.

"The public is looking at documentaries differently now, and that's partly the problem. Everyone's looking for the next Jane McDonald."

Nevertheless, Terrill insists that Jailbirds is not a docu-soap, and that the people in it have better things to do than allow themselves to become stars. Anyway, their time is not their own at the moment,

"It's true, the women in it are people you'll remember, people you'll talk about on the bus the next morning," he says.

"But if a woman has been a heroin addict for 11 years and has tried to commit suicide on her first week in prison, it doesn't seem to be the basis for the sort of celebrity that docu-soap stars tend to enjoy.

"These women have more important issues on their minds: survival, and the welfare of their children and their families. They're not going to worry about whether they'll get their five minutes of fame. That's not what it's about."

Terrill spent eight months at New Hall prison near Wakefield, filming the ten 30-minute episodes of Jailbirds. It was the Home Office who offered him access to the institution, after he insisted on shooting away from London.

Among his "characters" - the potential Maureen Reeses and Jeremy Spakes of 1999 - are Ivy, a 71-year-old who resorted to signing other people's cheques in order to pay her bills, and Melissa, a heroin addict of 17 who turned to burglary to feed her habit.

"I don't want people to be judgmental about these women," says Terrill. "That's not to say that this is preachy liberal stuff: 'Let's forgive these women because they're the gentle sex and they shouldn't be in prison'. Most of them should be in prison. But for the most part, they're ordinary people for whom life has gone a bit wobbly. They're not at all the hardened, scarred, butch criminal types of the old stereotype."

Nearly all the footage is contained within the walls of New Hall, but Terrill allowed himself a field trip to meet and film Melissa's parents. "You really identify with them," he says. "So many parents bring up their children in the way they think best, and then it all goes horribly wrong."

He accepts that people will inevitably see this as soap, especially given its serialised structure and its EastEnders-style, twice-weekly scheduling.

"Besides, he says, "people only ever remember me for The Cruise, which was a docu-soap.

"But Jailbirds is a classic documentary serial. Docu-soaps are associated with frothier, superficial storylines for early evening entertainment, rather than information or education, and I think that's a shame.

"I feel very strongly that the BBC must get back to serious public service broadcasting. That's our job. There are important messages to get across - particularly to youngsters who might already have thought about going down the heroin track.

"There are big issues here and I wouldn't want them to be undermined by this association with all the worst aspects of the docu-soap."

The former anthropologist, who describes The Cruise as "a blip in my career", and whose only previous experience of prisons was on filming expeditions overseas, says Jailbirds taught him a great deal about humanity.

"I don't want to be too apologetic about docu-soaps - there have been some very good ones and some very bad ones.

"Here, we've tried to move the genre on, to do something more relevant. And New Hall prison is certainly a more challenging environment than a cruise ship."

Converted for the new archive on 30 June 2000. Some images and formatting may have been lost in the conversion.