The new executive producer for The Sarah Jane Adventures, Nikki Wilson, spoke exclusively to Digital Spy about the upcoming fourth and fifth series of the show. You can read an extract below, or see the full interview here.

In series four the team will be meeting the Nightmare Man and the Shansheeth. What more can you tell us?

"The Nightmare Man is part of a really big emotional journey for Luke which involves him facing his fears and excitement about the future. The Shansheeth are vulture undertakers who get embroiled with the gang on a big adventure for the middle of the series."

Also the group will be visiting an alien world for the first time - will that be difficult production-wise?

"It's part of a bigger episode - we're not setting a whole two episodes on an adventure off Earth so it's fairly containable. With Sarah Jane it's very much rooted in contemporary London and Bannerman Road will always be the heart of the show. We're not Doctor Who so we don't go flying off around the universe but this is an opportunity for us to get a glimpse of that."

The series has never really needed much Doctor Who crossover and holds its own quite well, but David Tennant's appearance last year was an undoubted highlight. Did the success of that story make you reconsider crossovers?

"It's brilliant that this show had its origins in Doctor Who - Sarah Jane was a character created for Doctor Who. We will always maintain our links with the show but you're right, Sarah Jane is a show in its own right. Yes, there will always be room for crossovers in the future but it won't be a bigger feature than it has been in the past."