Sam Vincent and Jonathan Brackley, who wrote five episodes of Series 9, told CultBox: “The execs were adamant that, if Richard was leaving, we all had to find a fresh, different way for him to go (i.e. we couldn’t just blow yet another spook up!).”

They continued: “Lucas not being Lucas, and where that takes him, was something they hadn’t done before. Everyone felt that the darkness and mystery of both character and actor suited it, so we can’t recall that many viable alternatives being pitched around the table.”

Vincent and Brackley also admitted to being concerned about fans’ reaction to the story: “We knew there was dedicated core of Lucas and/or Richard fans who would want our heads on sticks. But you have to balance that against the desire to deliver a big, unexpected, shocking story and do something really ambitious – like turning your alpha male hero into someone else entirely.”

The pair joked: “We just hope the Peter Firth fans don’t react in the same way in Series 10 when we reveal that Harry has always actually been a cross-dressing quintuple agent and deranged serial arsonist working for North Korea.”

> Buy the Series 9 boxset on Amazon.

Spooks will return for a tenth series this Autumn.