A quick chat with Peter Firth about the current series of Spooks, screening on BBC1 on Monday evenings…

What did Ros’s death mean for Harry?
“Ros’s death is a cause of enormous grief to the team and particularly to Harry. When he finds who is culpable in her death he decides to exact summary justice on that person – which is quite unlike him.”

Can you tell us about Harry’s relationship with newcomer Beth Bailey?
“Years before she was a candidate for enrolment in MI5, but she was refused on the grounds the panel considered her to be self-interested, self-motivated and potentially arrogant. So she went off to work as a freelance mercenary in security services. In this series she performs an act of heroism and as a result finds her way back in MI5.”

Harry proposed to Ruth at the start of the series. Do we see a more romantic side to him?
“He proposed at Ros’s funeral so it’s not a particularly romantic proposal!”

We’re nearing the end of the series. Can you reveal any secrets?
“There’s a big surprise! There’s been a lot of suspicion in this series and it turns out the paranoia is justified on the most unexpected level!”

The show’s very unpredictable. Do you worry about your character being suddenly killed off?
“They used to kill you off at the drop of a hat, but it’s not quite like that any more.”

If you could choose how Harry dies, how would you do it?
“In slow motion!”