GREAT characters, dialogue + acting but unsatisfying + pointless in end

Realistically, what chance did Craven and Jedbergh ever have? I think that the whole point was that the two main characters never were going to achieve anything - they were up against too much - two Governments, big business, the Establishment, the lot. You could argue that Craven got what he wanted -he found out what had happened to Emma and why - once he'd got that, he didn't see any point in carrying on (he even tells Clemmie he doesn't know what he's going to do and he never really does come to a decision). Maybe Jedbergh got the ending he wanted - he's made his gesture (that nobody else in that room will ever forget), condemned Grogan to a pretty nasty death and then gone out with all guns blazing. There was no way that they were ever going to be the heroes of the hour, not with all that was stacked up against them - but at least they tried...
The fact that there wasn't a 'feelgood' ending meant that the overall message of the show was emphasised - Mankind is destroying the Earth and nobody in power seems to care or be prepared to do anything about it. Almost every character (apart from Craven, Jedbergh and Emma) ends up compromising themselves one way or another, whether it's bending the rules, informing on their comrades, selling out to their opponents, turning a blind eye to what's going on, or even sanctioning murder, and those that don't, end up being destroyed. It's a bleak conclusion - and it's meant to be. It's also far more powerful than a 'feelgood' ending would have been.