"Watch this space... viewers are in for a treat!" she said of the familiar faces making a grand return.
"We are going in a totally different direction for our 35th anniversary special, something very different which we are confident will be a real fan favourite. Watch this space."
Preece went on to elaborate: "Happily a couple of the characters that I would most like to see return will be doing so over the next 12 months, and at least one of those returns comes from a very unexpected direction."
BBC