Seth Stevenson writes about the differences between the American and British versions of Life on Mars:
Mol, who plays Sam’s U.S. love interest, is markedly blonder, thinner, and hotter than her BBC counterpart, yet has half the warmth and sex appeal. (Mol just seems to involuntarily exude off-putting brittleness at all times. I call it “Bridget Moynihan syndrome.”) Meanwhile, Sam’s U.S. upgrade—much like the one given to the Tim/Jim character on The Office—has him inhabiting an actor twice as handsome and five inches taller. This turns out to be a crucial casting misstep.
In the BBC show, Sam is a slightly built, measured, efficient, semi-emasculated modern man who is constantly at odds with Hunt’s sloppy, barrel-chested bluster. Among the show’s subtler strengths is the way it gradually allows the two men to meet each other halfway—with Hunt learning to overcome his baser instincts and Sam coming to see the value in occasionally knocking a few heads. On the ABC version, where Hunt is played by the scrawny and desiccated Keitel, Sam physically towers over his foil and thus the visual effect (along with the tension between the characters) is ruined. What use has Sam for an antiquated relic he can easily whup in both a battle of wits and a fistfight?
This is a pretty consistent difference between American and British television, and while I understand the rationale for Hollywood’s preference for extremely good-looking people, the British approach often serves them well. In particular, the more realistic casting helps capture the basic idea of the seventies as a time of decline and collapse. It also lets you set up the relationships between people in a more plausible kind of way.