> The UK series is very short which is typical. Indeed, there were 4 series each of 6 episodes, plus one special, so only 25 shows in total. IIRC in one of th

> The UK series is very short which is typical. Indeed, there were 4 series each of 6 episodes, plus one special, so only 25 shows in total. IIRC in one of the series extras this is talked about: because a series is just 6 episodes, producers are willing to give a wider range of ideas a chance, and if they do well, a second season (of six more episodes) isn't a big stretch. Notably there wasn't a fifth season because they all felt the concept had gone as far as it need to: they didn't want to "jump the shark".