Prime Time shows are made differently in Britain, and perhaps the biggest sign of this is season length. With few exceptions, Brits do not like Filler. In the United States prime time shows generally run 22-24 episodes per full-length season. British shows, on the other hand, tend to produce only about thirteen episodes a year if they're dramatic, or about six if they're comedies. See also Twelve-Episode Anime. Contrast Franchise Zombie - in the UK it's getting renewed that's difficult, rather than calling a halt.