How to find life after the stars go out

What do you do when you have a smash hit drama series and the central character - or even characters, plural - decide they've had enough? First, don't panic. Evidence suggests that this needn't be a fatal development. As Taggart, Dangerfield and Heartbeat have all amply demonstrated, even losing your biggest star needn't make a dramatic difference.

That must be a mighty consolation to the producers of Ballykissangel as they prepare for the return of the Sunday-night drama series next week. The third series will be the last to feature Father Peter and the local bar-owner Assumpta Fitzgerald, because the actors who play these characters (Stephen Tompkinson and Dervla Kirwan) have had enough of this charming corner of County Wicklow and are both turning their backs on Ballykissangel.

BBC drama chiefs were reluctant to speculate upon the likely impact on what has been one of the Beeb's biggest ratings bankers, but their press spokesmen, both in Belfast and London, were at pains to play down its significance, pointing out that Ballykissangel began to evolve into much more of an ensemble piece in the last series.

Maybe that's the point. The show is more important than the individual. Ballykissangel, like Heartbeat and Last of the Summer Wine, owes much of its success to its setting. It's not a coincidence that the hills around Holmfirth, the setting for Summer Wine, are alive to the sound of coach tours. Viewers like the place and the scenery almost as much as the characters.

The shows invariably have a central character with a specific job: a priest, a friendly village bobby, a tough-talking detective. The situations that come out of that job can easily be continued. And there is a sense of continuity from the support actors. Every star part has its well-meaning stooge. You might lose Nick Berry, you'll always have Bill Maynard as the lovable rogue.

Take Ballykissangel. The producers anticipated that Tompkinson and Kirwan would quit after three series, so they started to take steps to ensure that the show ceased to be a star vehicle for them. This delicate evolution will be turned up a few notches in the coming series.

Father Peter and Assumpta Fitzgerald won't feature in several of the episodes. Other characters, notably local businessman and entrepreneur Tony Doyle (played by Brian Quigley) and his daughter Niamh Egan (Tina Kellegher) will have their profile boosted, as will other inhabitants of the village.

The same strategy is being pursued in the North Moors village of Aidenfield as the producers of Heartbeat use every creative trick in the book to survive the loss of heart-throb Nick Berry. The 34-year-old actor became synonymous with the Sixties rural police drama, which has regularly pulled in 16 million viewers over the past seven years.

Executive producer Keith Richardson can point to some success since the first three episodes without Berry have averaged 13.5 million viewers. "The audience are happy to see people go when it happens in a natural fashion," he says. "It can even add to the authenticity of the drama if it is handled well."

Richardson says he was "really worried" when Niamh Cusack (who played PC Rowan's doctor wife in the first couple of series) left the cast. It was decided that she should develop cancer and die after giving birth to their first child.

"There was a heroic exit and tons of tears," Richardson recalls. "And people were just as keen to watch the next series and see how Nick coped."

Berry softened the blow for Yorkshire TV by agreeing to star in a one- off video charting PC Rowan's decision to emigrate from Aidenfield and enlist as a Mountie in Canada.

There is always the possibility that this could turn out to be the pilot of a future series. But no one up in Leeds is banking on that. Instead, they're putting all their creative efforts, like their counterparts on Ballykissangel, into bringing other characters to the fore. The focus will broaden to the village as a whole.

The same might have happened to Hamish Macbeth when Robert Carlyle quit after the third series, but everyone involved in that enterprise decided it was best to go out on a high.

They could easily have drawn a different lesson from another Scottish drama, Taggart, which has not only survived the death of its eponymous star, Mark MacManus, but is continuing to pull in more than 10 million viewers. That is lower than the 12 million it used to get, but this reflects a general fall in ITV's ratings.

Scottish Television's drama supremo Robert Love says the key to continuing success was the decision to develop other characters, such as Detective Inspector Jardine (played by James Macpherson) and Detective Sergeant Jackie Reid (Blythe Duff) when McManus's health first started to fail.

"We were also convinced we could make the series work because we knew we could maintain many of the main ingredients - such as the setting, the production values and the strong scripts," says Love, adding: "We never seriously contemplated getting anyone else to step into Mark's role."

The plots, he notes, had long ago ceased to revolve around DCI Taggart himself and had become a much more multi- dimensional drama about murder and mystery on Clydeside. Still, it was considered wise to keep the title Taggart.

"None of the other options we discussed, such as The Taggart Files or Taggart's Team, had the same resonance," says Love. "Besides, we'd built the Taggart brand."

The BBC hospital drama Casualty has kept up its popularity with a constantly changing cast. Those who have swiftly passed through its corridors include Nigel Le Vaillant, who played Dr Julian Chapman. Le Vaillant left to star in Dangerfield. But he also tired of being a dashing police pathologist in a four-wheel drive and quit that role after four series.

Dangerfield has continued, of course, with Nigel Havers taking over the practice in a different role - that of heart surgeon Jonathan Paige.

Obviously there are some drama series which couldn't survive the loss of their central character. It is impossible to imagine Cracker without Robbie Coltrane and Silent Witness would scarcely be the same without Amanda Burton.