WCXX

"It's very delicate, very special and beautifully written."

The fourth series is set in 1922 and begins six months after the death of Matthew Crawley, who met an abrupt end in a car crash at the end of the Christmas special.

His death has left the family facing disagreement about who should run the estate whilst also being saddled with death duties.

Although Lady Mary is deeply grieving, a string of potential suitors are expected to try their hand at romancing her, including an aristocratic old school friend, Lord Anthony Gillingham, played by Tom Cullen.

Co-creator Gareth Neame said: "Although Mary is not really open to moving on from Matthew at all that does not mean there is not interest from other men."

Neame acknowledged that Matthew's death would have brought an abrupt end to Christmas Day festivities for millions of viewers.

But he said: "Drama is about these twists and turns and surprises.

"As shocking as all of that was, those life and death situations will happen to families from time to time.

"The show has got very heightened moments of drama it has got big twists and turns."

Allen Leech, who plays former chauffeur Tom Branson, is set to take a more prominent role in the running of Downton, and admitted that now his character has his own car, he no longer has to worry about driving around Dame Maggie Smith, the Dowager Countess.

"I prefer not having the worry of Maggie Smith sitting in the back as you are hurtling towards the house and being told to stop on a very specific mark," he joked.

Dame Kiri, who performs Giacomo Puccini's O Mio Babbino Caro and Antonin Dvorak's Songs My Mother Taught Me during the episode, said she had always been fascinated by Dame Nellie's career.

"I had a log sheet of all the performances she did and saw how much she earned and how many roles she played," she said.

"Her wage for one year would have been about £3 million in today's money.

"Songs My Mother Taught Me was one of her favourite songs and she performed it everywhere. "We've got a recording of her doing it so we tried to copy it and it's very beautifully done and very special so we had to put that one in.

"I was trying to stay true to the character because as (show writer) Julian Fellowes said 'she's the only true character' that actually lived."

New Zealand-born Dame Kiri has a few lines and will interact with the Earl of Grantham and Branson during the show.

She revealed that she enjoyed her two days on set at Highclere Castle in Hampshire so much that she has named one of her dogs Abbey, after the show.

However, she disclosed that Lady Carnarvon, the owner of Highclere, who has two blonde labradors and three spaniels, did not want her own two dogs "anywhere near the place".

Lady Carnarvon has previously admitted that she usually asks for no dogs to be brought to the castle after one of the labradors, Percy, proved unwilling to tolerate a rival pooch on set.