Outgoing timelord David Tennant is set to make a special appearance on spin off show The Sarah Jane Adventures.

Russell Davies told the BBC that Tennant’s stint will be a full appearance and not a minor cameo.

Elisabeth Sladen plays Sarah Jane and starred in Doctor Who with Jon Pertwee and Tom Baker between 1973 and 1976. She said she was “absolutely over the moon” to now be co-starring alongside Tennant.

“It’s fantastic news that Sarah Jane is going to spend some time working with the Doctor again and is testament to just how successful this CBBC series is.”

Davies said: “Viewers thought they may have to wait until November for the next full episode of Doctor Who, but this is an extra special treat.

“And it’s not just a cameo from David.

“This is a full-on appearance for the Doctor as he and Sarah Jane face their biggest threat ever.”