Alex Kingston will return for the fifth series of Doctor Who, it has been confirmed.

The former ER actress was spotted alongside new Doctor Matt Smith and sidekick Karen Gillian on the first day of filming in Cardiff for the new series, due to be shown next spring.

Fans last saw Alex in the series four two-parter Silence in the Library and Forest of the Dead, penned by new executive producer Steven Moffat.

In those episodes, Alex’s character River Song (pictured), claimed she knew The Doctor from an unspecified point in his future.

It’s not known if Alex will be playing River Song in the new series – but The Sun suggests that the actress could appear as the Doctor’s wife!

A BBC spokesman told Wales Online: “Viewers will have to wait and see who she plays and how her character fits into the series.”

Alex is currently starring in the BBC1 drama Hope Springs.