Hot on the heels of the release of a prequel featuring new character Hal comes confirmation that Sinead Keenan is not reprising her role as werewolf Nina for the fourth season of Being Human.

“It is with a very heavy heart & a little relief that I can now tell you that I will not b appearing in S4 of Being Human,” she posted on Twitter. “I cannot tell u how difficult it was to make the decision to leave. I’ve had 3 wonderful years… some of the best I’ve had in my acting career.”  She has not filmed a farewell scene for her character.

Being Human is expected to return to BBC Three later this month. Keenan’s werewolf co-star Russell Tovey is also leaving the show during the fourth year; Aidan Turner’s character was killed off in the series three finale.

In a press release for the new season, creator Toby Whithouse explained: “Not only would it be our first series without Aidan, but Russell had decided that series 4 would be his last, and Sinead had decided that her Being Human journey had come to an end after series 3. The mountain before us seemed even higher than usual.

“But once we’d stopped rocking and shaking, we saw series 4 as an opportunity: we could invent new characters, expand the show in different directions, create new worlds and monsters and heroes, and add new layers to the overarching Being Human mythology.”