It's been confirmed by the BBC that 58 year old actress, Lindsay Duncan will play a character
called Adelaide in the second of the planned four 2009-10 specials.
"I'm thrilled to be involved in Doctor Who. I've never done anything like
this before and I'm really looking forward to working with David Tennant and the Doctor Who team."
Duncan previously appeared in shows such as Rome and Criminal Justice.
The special is rumoured to air at around Summer or Halloween time and will be preceded by the Easter special, Planet of The Dead, which stars Michelle Ryan as the companion.