Doctor Who is set to take a trip back in time with his new companion to the Roman Empire.

The doctor, played by David Tennant, has been joined by comedienne Catherine Tate as his sidekick in the next series.

The couple will arrive on the eve of the historic eruption of Mount Vesuvius in the city of Pompeii in AD 79.

Although the pair did travel to Rome to film the story-line, the scenes were recreated in a studio set that was transformed to look like historical Italy.

The TV couple will be faced with the difficult decision to either rescue the residents or leave them to fend for themselves.

Peter Capaldi, who played spin doctor Malcolm Tucker in The Thick of It, will also feature in the show as banker Caecilius.

Doctor Who executive producer and head writer Russell T Davies said: "Arriving in Pompeii marks the start of another exciting adventure for The Doctor and Donna."

He added: "Donna is stunned to find herself in the midst of history's most famous volcanic eruption.

"Viewers can expect many more ambitious storylines and a whole host of guest stars in 2008."

The fourth series is set to hit TV screens next Spring but the fifth instalment has been postponed until 2010, fuelling speculation about David Tennant's future with the show.

A special Christmas episode starring Kylie Minogue will be broadcast in December.

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