He told The Daily Telegraph: “We would have loved to keep him. We would have loved to keep Jessica [Brown Findlay as Sybil] too. We have always tried to persuade him to stay. He had done fantastically well for the series and his creation of Matthew was terrific.”

“If [Dan Stevens] had been prepared to come back for maybe two or three episodes in a series, that would be different. Then we could have had a foreign posting or invented a career that would have made it possible for him to be away. Otherwise we would have had to make this tremendously successful love affair between Mary and Matthew unhappy, which I didn’t feel would be believable.

“For them to then separate and Matthew never set eyes on his son again would not be believable either. So we didn’t really have any option. By him dying, their love can remain in tact.”

Lord Fellowes joked: “Matthew will be dead. Mary will not find Matthew in the shower; that I can promise.”

An ITV spokeswoman commented earlier this week: “After three successful series and two Christmas editions of Downton Abbey, Dan Stevens decided not to renew his contract beyond the initial three years he had been contracted. We wish him every success for the future. Michelle Dockery will be returning to her role as Lady Mary in Series 4 which begins production in February. Over the last three years, audiences across the world have been captivated by the ups and downs of Mary and Matthew’s relationship, culminating in their wedding.”

She continued: “Fans have enjoyed what has become a solid and loving marriage. It is for this reason that the Producers decided Matthew and Mary could not simply be estranged or parted, resulting in his untimely and tragic death at the end of the Christmas episode. In the next series, alongside all the usual drama, comedy and romance involving the much loved cast of characters, viewers will see Mary adjusting to her life and attempting to move on without the man she loved.”

A fourth series and Christmas 2013 special were confirmed by ITV last month.

What did you think of the Christmas special? Let us know below…

> Buy the complete Series 1-3 boxset on Amazon.

Watch the Series 3 trailer…