The BBC has already recorded a final episode to the current series that leaves open the possibility of new occupants of the shared house in any following series.
Sources close to the programme said yesterday that the actors who play Ferdy, Anna, Miles, Egg and Milly will have their schedules booked up before the BBC decided which, if any of them it wants for another series.
This Life is one of the BBC's biggest projects and it is difficult to get actors to commit themselves to recording 21 45-minute episodes without a long notice period.
One possibility being discussed is that two of the current characters may stay on in the house for a few episodes while new characters are introduced to viewers. Fans of the programme at the BBC are known to be worried at the delay in commissioning the series because it took until well into the second series for viewers to get to know the characters and start following the programme avidly.
Now This Life attracts up to 4 million viewers which makes it one of BBC 2's best audience generators, bigger than the much more hyped Friends and ER on Channel 4.
Recent criticism of the BBC's drama output by director general John Birt has stung the corporation's drama department and it is unhappy about the possibility of losing one of its successful projects just as it is starting to become a hit.
"Channel 4 spent most of the budget for foreign acquisitions to secure ER and Friends for a few more years and Channel 5 was champing at the bit for them, while at the BBC they are dragging their feet over re-commissioning a bona fide hit," said a source close to the programme.
A BBC spokesman yesterday confirmed that no third series had been commissioned, but refused to comment on changes to characters.
The programme is made by World Productions, the production company owned by Tony Garnett who also makes hits such as Ballykissangel and Between The Lines.
Mr Garnett is currently in discussion with Channel 4's new boss Michael Jackson about producing long-running drama serials for Channel 4.
This Life has earned plaudits for sustaining long runs by using different writers for each episode, while keeping the overall feel of the drama the same. It is considered a new way of producing popular drama without resorting to soap-opera formulas.
In case you've missed it, the story so far...
Employing the shaky hand-held camera techniques that distinguished `yoof' programmes, This Life follows the love-lives and careers of a group of twentysomething lawyers who share a house in south London.
Its popularity is based on a realistic approach to drink, drugs, nicotine and casual sex. It employs soap opera tricks to hook the viewer, including infidelities shared with viewers.
The main characters are: barrister Anna, the sexually accident-prone lawyer with a longing for flatmate Miles.
Miles, in the same chambers as Anna, is the obnoxious rich kid who recently got engaged, but then slept with Anna.
Milly, the control freak who is having an affair with her boss in the solicitors' firm, although she shares a bed with Egg.
Egg, who dropped out of firm where he worked with Milly and is running a cafe with a single mother.
Ferdy is a sexually confused Mexican dispatch rider who is forever being mistaken for an American Indian. Paul McCann