Its characters have aged 14 years since they were first introduced in an RSC production at the Pit in 1982. If Peter Flannery, the author whose patient faith in his own work has been tested so extensively, could write up the marathon in compressed dramatic form, it would doubtless make a gripping screenplay with a twisting, turning plot that would reduce its audience to the state of nervous exhaustion suffered all these years by the author. Whether anyone would believe it is another matter.
Though no drama can challenge Our Friends in the North for sheer length of gestation, it is actually quite a common story. Of course, for well- documented reasons, drama does take a long time to get the go-ahead these days - everyone knows that a commissioning editor's favourite colour is amber. But, just as there are subtly different ways to tell a story, there are any number of subtly different ways in which a project can deccelerate almost to a complete standstill.
It is not widely known that Pride and Prejudice could have appeared much earlier than the end of last year. Andrew Davies completed three parts of the series at the end of the 1980s, but with memories of Fay Weldon's version still fresh, Davies's adaptation of Middlemarch was allowed to leapfrog it.
Other great dramas have been prey to generic confusion. GBH stumbled into being as a 1,000-page novel, and only by painful attrition did Alan Bleasdale pare it down to the nine-hour slip of a thing seen several years later. Jimmy McGovern's Priest started life as an idea for a Brookside character in 1983, then mutated into a series called The Ten Commandments, which the BBC rejected. It was commissioned as a three-parter, evolved into a four-parter, and was made as a "Screen Two" that was so well received at festivals it was given a theatrical release 12 years after the character was born.
McGovern was so wedded to the project that he was initially undecided whether to shelve it to script what became known as Cracker. In the end it was the success of the cop show that turned McGovern into piping hot property and allowed Priest to see the green light at the end of a particularly long and dark tunnel.
Like McGovern, one of Flannery's impediments was the vision-thing syndrome. In this fairly widespread condition, commissioning editors give a wide berth to original scripts that make a challenging personal statement about contemporary Britain.
It may soft-peddle an anti-ageist agenda, but no one would accuse Hetty Wainthrop Investigates of being a passionately original vision. It did however, take nine years to reach BBC1 in its present form. What no one seems to have remembered is that Missing Persons, the original novel that introduced the character, was made into a two-hour film by Yorkshire in 1987. Then, as now, Patricia Routledge played Hetty and let it be known that she would like to make a series. She had already read David Cook's novel on the radio and has remained committed to the project despite an avalanche of rejections and false starts.
Yorkshire's proposal for a series was first turned down by ITV under the flexipool system in which, as all the regional companies financed one another's projects, they also enjoyed the right to veto one another. In a climate of you-stab-my-back-I'll-stab-yours, it was blackballed by someone who had doubtless had something of their own turned down. "Someone said it was too comfortable,'' says Cook, "too bedroom-slippers-and-pipe.''
If flexipool was the biggest hurdle at ITV, at the BBC it was the ceaseless and myriad personnel changes in the drama department that claimed so many dramas. One head of drama rejected Hetty, but once he moved on the project was accepted.
That was three and a half years ago, but then Patricia Routledge entered a long period of unavailability while she played another old battleaxe in Keeping Up Appearances. When Routledge finally parted company from Hyacinth Bucket, the BBC were desperate to give her another vehicle, and Cook's scripts had to be hastily relocated from summer to winter. Thanks to the nine-year gestation, it misleadingly looks as if the BBC had commissioned Cook to knock up something for their star.
Selling Hitler, the story of the forged Hitler diaries, took a more modest but still bronze-medal-winning five years to reach the screen. Although the BBC briefly expressed an interest, it was an ITV project from day one. Its initial problem was finding a writer to come up with a sensible adaptation.
The option was bought by Euston Films soon after the book by Robert Harris was published. A writer came on board but soon leapt off again when Euston decided to seek co-production finance and make it more commercial.
Harris worked hard on his fixed grin as the comedy specialists announced a broader, farcical version. "There was a scene at Longleat with the Marquess of Bath, the Hitler collector,'' recalls Harris. "They had this idea of Nazis driving round in cars throwing rabbis out of windows to the lions."
Then Howard Schuman, in the throes of failing to get his own lengthy personal statement about monetarism on to the screen, stepped in with a script everyone liked. Except for ITV's viper-infested flexipool. "It was turned down,'' says Schuman, the author of Rock Follies, "on the grounds that I could not write a commercially successful serial.''
Eventually Euston and Thames agreed to fund it themselves. Schuman and the late, great producer Andrew Brown schlepped around America in search of co-production money. In the end, Thames spent pounds 4m on it in a last desperate bid before the franchise came up for renewal, to prove they could make quality drama. They turned in a wonderful series and duly lost out to Carlton.
"Very early on I took a philosophical view of this,'' says Harris, "which is that these things aren't made. And that's one of the reasons why I'd never want to write a screenplay." And yet the whole process is about to start again. Enigma has been optioned by Paramount, and the services of Tom Stoppard have been all but secured to adapt it. "And, who knows?" says Harris. "It may be made this year. It may be made in five years. It may never be made.''
n 'Our Friends in the North' starts BBC2 at 9pm on Mon