Two assistants to join the Doctor

It could get crowded inside the Tardis during the next series of Doctor Who as the Time Lord will have two assistants.

Fans watched Martha leave the Doctor to look after her family during the series finale, but TV bosses say she will be back halfway through the fourth series.

In the meantime, the Doctor has got a vacancy for a new companion - but show insiders haven't said who it is yet.

Writer Russell T Davies said Martha - played by Freema Agyeman - had been a huge part of the show's success.

Click here for our scary Doctor Who pic gallery

The fourth series of Doctor Who goes into production in July and will be back on our screens with a special called Voyage Of The Damned at Christmas.