Let's go straight to the very end of the finale and that ambiguous freeze frame ending - was it always planned to end like that or were any alternative endings filmed?
"We always planned to leave it on a cliffhanger. It gives us more to play with if and when we come back. So yes, it was very intentional on our part. I liked the fact that it's as much a cliffhanger about one of our characters as it is about the events of the bomb. Is Rachel going to survive and is the bomb going to go off? Neither were resolved before the end and I personally quite liked that. It's paying homage to the Spooks model."
That final 'negative effect' on the final shot could be seen as suggesting that the bomb has gone off...
"Ah, because of the whiteout. That's interesting! Yeah, that's unintentional. That's just because we always go for a negative image."
Are plans underway for a second series?
"We are still waiting to hear from the BBC about a second series. I would hope we would know within the next couple of weeks."
Are the cast contracted for another year?
"Most of them are, yes. I can’t say who, but most of them are."
At the beginning of the series the show received a lot of criticism for being associated with Spooks. Do you think having that brand association prevented some viewers from judging the show in its own right?
"I think that is always the danger with a spinoff, certainly. It was a big discussion between the BBC and Kudos and we expected that kind of backlash. It's interesting for BBC Three to have brought, probably, an audience to the channel that wouldn't have come to it if it wasn't called Spooks. But I think there is a fair argument for the fact that it is a very different show to Spooks and therefore did attract criticism for it. It was taking an overall view that everyone wanted to keep the brand - and that was a big part of the commission as well."
BBC Three targets the youth demographic. Were there any concessions you had to make, such as the early nightclub scenes, to pander to that audience?
"I think that it's tricky. It was always tricky. You're making an espionage show for 16-24s and a big part of the premise was thinking about what situation would mean that young spies were recruited to MI5 and then keeping characters that our audience can engage with. The audience should be thinking could they, would they or should they, in an event like that, become spies themselves. Seeing them having fun felt right for those characters - clubbing and all the rest of it goes on for that age group. You've got an important job, but you still need to let your hair down."
Looking back, what do you think worked best on Code 9?
"That's a very good question. I think the cast are superb - I'm really thrilled with how they worked out. It was a very long process to bring that group of people together and I think we have some very exciting actors of the future in that mix. I loved the times where you saw more of the 2013 world - the checkpoints and the anti-radiation stuff. The subtle things that showed we were in a world that was slightly different to the world we're in now. Prospect Towers just in itself was a really interesting world to explore, where all these people from London had been rehoused… it's something we'd like to explore if we get a second series."
The premise of the show - that the 2012 London games have been targeted by terrorists - is a very real threat. Were there any problems, perhaps with the BBC, about going ahead with such a storyline?
"Yes, of course. There has been a lot of discussion with editorial policy and the channel and the commissioners. I think that it's been handled in a way that we set it up without referring to it by name or number and hopefully it's just establishing a context. But yes, there was a lot of discussion about it."
> Click here for our review of the Spooks: Code 9 finale