Anyone else watch this top-notch BBC drama? I'm always dubious about anything released by the BBC, and this is the few programmes I will not only watch on BBC 1, but will also enjoy immensely. Although it may lose the niche status it enjoyed in weekdays by being bumped up to Prime Time Sunday-evening viewing, it started with a bang and I think it's a real testament to the writers' credibility and reliability to keep up to date and challenge major social issues like terrorism instead of shying away slightly by drawing thick lines between good and bad. I can see series 5 being just as good as the previous four.