Alex Kingston: 'River Song could return to Doctor Who'

Alex Kingston has hinted that River Song could return to Doctor Who.

The actress, who will appear in the new series of Upstairs Downstairs, told talkshow host Graham Norton that she may resume her Who role.

"You may see her again. Who knows?" she teased. "Let's just say, Upstairs Downstairs and Doctor Who don't film at the same time."

Kingston also admitted that she had known "for a very long time" that her character was secretly the daughter of Amy Pond (Karen Gillan).

"I knew... for the whole of the last series," she confessed. "[The other actors] didn't know and they were constantly trying to get it out of me. They discovered it in that episode ['A Good Man Goes To War'] when they read the script."

Karen Gillan will exit Doctor Who alongside her on-screen husband Arthur Darvill (Rory) mid-way through the next series.

Series star Matt Smith recently indicated that he currently has "no plans to leave" the sci-fi drama.

Doctor Who will return to BBC One in late 2012. The Graham Norton Show - featuring Kingston, This Means War star Reese Witherspoon, comedian Reginald D Hunter and British indie band The Musgraves - will air on Friday at 10.35pm on BBC One.

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Watch Matt Smith discuss his future with Doctor Who below: