They dumped him? I had heard that he left -- he was sick of Jeff.
Coyle’s decision to leave the popular series was motivated by his future career. His fear, as with many fellow actors, was that of being typecast: “I was very keen that that character didn’t stick with me. It’s the kind of character that does. I’m an actor and I want to be an actor when I’m 60. It’s a lifelong process, why cut it off by boxing yourself into a little pigeon hole early on?”
In an interview with one of the co-writers (the husband in the husband and wife team), he made it seem like after the 3rd season, Jeff had some introspection and decided to totally divorce himself from the show-- thus, no "Jeff Leaves" episode. The writer said the show's folks were kind of annoyed about it. It had to have been a tough decision, and that's why he did Strange next-- a scary/drama show. But, I always have trouble seeing actors play different roles, especially in the BBC shows. Martin Freeman will always be "Tim"-- even when I see him in Ali G Indahouse and The Robinsons. Same with Sarah Alexander playing "Susan." She played in "The Worst Week of My Life" as an engaged woman and I thought it was too bad that her relationship with Steve didn't work out. :-)